diff --git a/packages/babel-helpers/src/helpers-generated.ts b/packages/babel-helpers/src/helpers-generated.ts
index 69f07f678f22..9ab09c8d97cb 100644
--- a/packages/babel-helpers/src/helpers-generated.ts
+++ b/packages/babel-helpers/src/helpers-generated.ts
@@ -15,7 +15,7 @@ function helper(minVersion, source) {
 export default Object.freeze({
   applyDecs: helper(
     "7.17.0",
-    'function createMetadataMethodsForProperty(metadataMap,kind,property){return{getMetadata:function(key){if("symbol"!=typeof key)throw new TypeError("Metadata keys must be symbols, received: "+key);var metadataForKey=metadataMap[key];if(void 0!==metadataForKey)if(1===kind){var pub=metadataForKey.public;if(void 0!==pub)return pub[property]}else if(2===kind){var priv=metadataForKey.private;if(void 0!==priv)return priv.get(property)}else if(Object.hasOwnProperty.call(metadataForKey,"constructor"))return metadataForKey.constructor},setMetadata:function(key,value){if("symbol"!=typeof key)throw new TypeError("Metadata keys must be symbols, received: "+key);var metadataForKey=metadataMap[key];if(void 0===metadataForKey&&(metadataForKey=metadataMap[key]={}),1===kind){var pub=metadataForKey.public;void 0===pub&&(pub=metadataForKey.public={}),pub[property]=value}else if(2===kind){var priv=metadataForKey.priv;void 0===priv&&(priv=metadataForKey.private=new Map),priv.set(property,value)}else metadataForKey.constructor=value}}}function convertMetadataMapToFinal(obj,metadataMap){var parentMetadataMap=obj[Symbol.metadata||Symbol.for("Symbol.metadata")],metadataKeys=Object.getOwnPropertySymbols(metadataMap);if(0!==metadataKeys.length){for(var i=0;i<metadataKeys.length;i++){var key=metadataKeys[i],metaForKey=metadataMap[key],parentMetaForKey=parentMetadataMap?parentMetadataMap[key]:null,pub=metaForKey.public,parentPub=parentMetaForKey?parentMetaForKey.public:null;pub&&parentPub&&Object.setPrototypeOf(pub,parentPub);var priv=metaForKey.private;if(priv){var privArr=Array.from(priv.values()),parentPriv=parentMetaForKey?parentMetaForKey.private:null;parentPriv&&(privArr=privArr.concat(parentPriv)),metaForKey.private=privArr}parentMetaForKey&&Object.setPrototypeOf(metaForKey,parentMetaForKey)}parentMetadataMap&&Object.setPrototypeOf(metadataMap,parentMetadataMap),obj[Symbol.metadata||Symbol.for("Symbol.metadata")]=metadataMap}}function createAddInitializerMethod(initializers){return function(initializer){assertCallable(initializer,"initializers"),initializers.push(initializer)}}function memberDecCtx(base,name,desc,metadataMap,initializers,kind,isStatic,isPrivate){var kindStr;switch(kind){case 1:kindStr="accessor";break;case 2:kindStr="method";break;case 3:kindStr="getter";break;case 4:kindStr="setter";break;default:kindStr="field"}var metadataKind,metadataName,ctx={kind:kindStr,name:isPrivate?"#"+name:name,isStatic:isStatic,isPrivate:isPrivate};if(0!==kind&&(ctx.addInitializer=createAddInitializerMethod(initializers)),isPrivate){metadataKind=2,metadataName=Symbol(name);var access={};0===kind?(access.get=desc.get,access.set=desc.set):2===kind?access.get=function(){return desc.value}:(1!==kind&&3!==kind||(access.get=function(){return desc.get.call(this)}),1!==kind&&4!==kind||(access.set=function(v){desc.set.call(this,v)})),ctx.access=access}else metadataKind=1,metadataName=name;return Object.assign(ctx,createMetadataMethodsForProperty(metadataMap,metadataKind,metadataName))}function assertCallable(fn,hint){if("function"!=typeof fn)throw new TypeError(hint+" must be functions")}function assertValidReturnValue(kind,value){var type=typeof value;if(1===kind){if("object"!==type||null===value)throw new TypeError("accessor decorators must return an object with get, set, or initializer properties or void 0");void 0!==value.get&&assertCallable(value.get,"accessor.get"),void 0!==value.set&&assertCallable(value.set,"accessor.set"),void 0!==value.initialize&&assertCallable(value.initialize,"accessor.initialize")}else if("function"!==type){var hint;throw hint=0===kind?"field":10===kind?"class":"method",new TypeError(hint+" decorators must return a function or void 0")}}function applyMemberDec(ret,base,decInfo,name,kind,isStatic,isPrivate,metadataMap,initializers){var desc,initializer,value,decs=decInfo[0];isPrivate?desc=0===kind||1===kind?{get:decInfo[3],set:decInfo[4]}:3===kind?{get:decInfo[3]}:4===kind?{set:decInfo[3]}:{value:decInfo[3]}:0!==kind&&(desc=Object.getOwnPropertyDescriptor(base,name)),1===kind?value={get:desc.get,set:desc.set}:2===kind?value=desc.value:3===kind?value=desc.get:4===kind&&(value=desc.set);var newValue,get,set,ctx=memberDecCtx(base,name,desc,metadataMap,initializers,kind,isStatic,isPrivate);if("function"==typeof decs)void 0!==(newValue=decs(value,ctx))&&(assertValidReturnValue(kind,newValue),0===kind?initializer=newValue:1===kind?(initializer=newValue.initialize,get=newValue.get||value.get,set=newValue.set||value.set,value={get:get,set:set}):value=newValue);else for(var i=decs.length-1;i>=0;i--){var newInit;if(void 0!==(newValue=(0,decs[i])(value,ctx)))assertValidReturnValue(kind,newValue),0===kind?newInit=newValue:1===kind?(newInit=newValue.initialize,get=newValue.get||value.get,set=newValue.set||value.set,value={get:get,set:set}):value=newValue,void 0!==newInit&&(void 0===initializer?initializer=newInit:"function"==typeof initializer?initializer=[initializer,newInit]:initializer.push(newInit))}if(0===kind||1===kind){if(void 0===initializer)initializer=function(instance,init){return init};else if("function"!=typeof initializer){var ownInitializers=initializer;initializer=function(instance,init){for(var value=init,i=0;i<ownInitializers.length;i++)value=ownInitializers[i].call(instance,value);return value}}else{var originalInitializer=initializer;initializer=function(instance,init){return originalInitializer.call(instance,init)}}ret.push(initializer)}0!==kind&&(1===kind?(desc.get=value.get,desc.set=value.set):2===kind?desc.value=value:3===kind?desc.get=value:4===kind&&(desc.set=value),isPrivate?1===kind?(ret.push((function(instance,args){return value.get.call(instance,args)})),ret.push((function(instance,args){return value.set.call(instance,args)}))):2===kind?ret.push(value):ret.push((function(instance,args){return value.call(instance,args)})):Object.defineProperty(base,name,desc))}function applyMemberDecs(ret,Class,protoMetadataMap,staticMetadataMap,decInfos){for(var protoInitializers,staticInitializers,existingProtoNonFields=new Map,existingStaticNonFields=new Map,i=0;i<decInfos.length;i++){var decInfo=decInfos[i];if(Array.isArray(decInfo)){var base,metadataMap,initializers,kind=decInfo[1],name=decInfo[2],isPrivate=decInfo.length>3,isStatic=kind>=5;if(isStatic?(base=Class,metadataMap=staticMetadataMap,0!==(kind-=5)&&(initializers=staticInitializers=staticInitializers||[])):(base=Class.prototype,metadataMap=protoMetadataMap,0!==kind&&(initializers=protoInitializers=protoInitializers||[])),0!==kind&&!isPrivate){var existingNonFields=isStatic?existingStaticNonFields:existingProtoNonFields,existingKind=existingNonFields.get(name)||0;if(!0===existingKind||3===existingKind&&4!==kind||4===existingKind&&3!==kind)throw new Error("Attempted to decorate a public method/accessor that has the same name as a previously decorated public method/accessor. This is not currently supported by the decorators plugin. Property name was: "+name);!existingKind&&kind>2?existingNonFields.set(name,kind):existingNonFields.set(name,!0)}applyMemberDec(ret,base,decInfo,name,kind,isStatic,isPrivate,metadataMap,initializers)}}pushInitializers(ret,protoInitializers),pushInitializers(ret,staticInitializers)}function pushInitializers(ret,initializers){initializers&&(initializers.length>0?(initializers=initializers.slice(),ret.push((function(instance){for(var i=0;i<initializers.length;i++)initializers[i].call(instance);return instance}))):ret.push((function(instance){return instance})))}function applyClassDecs(ret,targetClass,metadataMap,classDecs){if(classDecs.length>0){for(var initializers=[],newClass=targetClass,name=targetClass.name,ctx=Object.assign({kind:"class",name:name,addInitializer:createAddInitializerMethod(initializers)},createMetadataMethodsForProperty(metadataMap,0,name)),i=classDecs.length-1;i>=0;i--){var nextNewClass=classDecs[i](newClass,ctx);void 0!==nextNewClass&&(assertValidReturnValue(10,nextNewClass),newClass=nextNewClass)}ret.push(newClass),initializers.length>0?ret.push((function(){for(var i=0;i<initializers.length;i++)initializers[i].call(newClass)})):ret.push((function(){}))}}export default function applyDecs(targetClass,memberDecs,classDecs){var ret=[],staticMetadataMap={},protoMetadataMap={};return applyMemberDecs(ret,targetClass,protoMetadataMap,staticMetadataMap,memberDecs),convertMetadataMapToFinal(targetClass.prototype,protoMetadataMap),applyClassDecs(ret,targetClass,staticMetadataMap,classDecs),convertMetadataMapToFinal(targetClass,staticMetadataMap),ret}',
+    'function createMetadataMethodsForProperty(metadataMap,kind,property){return{getMetadata:function(key){if("symbol"!=typeof key)throw new TypeError("Metadata keys must be symbols, received: "+key);var metadataForKey=metadataMap[key];if(void 0!==metadataForKey)if(1===kind){var pub=metadataForKey.public;if(void 0!==pub)return pub[property]}else if(2===kind){var priv=metadataForKey.private;if(void 0!==priv)return priv.get(property)}else if(Object.hasOwnProperty.call(metadataForKey,"constructor"))return metadataForKey.constructor},setMetadata:function(key,value){if("symbol"!=typeof key)throw new TypeError("Metadata keys must be symbols, received: "+key);var metadataForKey=metadataMap[key];if(void 0===metadataForKey&&(metadataForKey=metadataMap[key]={}),1===kind){var pub=metadataForKey.public;void 0===pub&&(pub=metadataForKey.public={}),pub[property]=value}else if(2===kind){var priv=metadataForKey.priv;void 0===priv&&(priv=metadataForKey.private=new Map),priv.set(property,value)}else metadataForKey.constructor=value}}}function convertMetadataMapToFinal(obj,metadataMap){var parentMetadataMap=obj[Symbol.metadata||Symbol.for("Symbol.metadata")],metadataKeys=Object.getOwnPropertySymbols(metadataMap);if(0!==metadataKeys.length){for(var i=0;i<metadataKeys.length;i++){var key=metadataKeys[i],metaForKey=metadataMap[key],parentMetaForKey=parentMetadataMap?parentMetadataMap[key]:null,pub=metaForKey.public,parentPub=parentMetaForKey?parentMetaForKey.public:null;pub&&parentPub&&Object.setPrototypeOf(pub,parentPub);var priv=metaForKey.private;if(priv){var privArr=Array.from(priv.values()),parentPriv=parentMetaForKey?parentMetaForKey.private:null;parentPriv&&(privArr=privArr.concat(parentPriv)),metaForKey.private=privArr}parentMetaForKey&&Object.setPrototypeOf(metaForKey,parentMetaForKey)}parentMetadataMap&&Object.setPrototypeOf(metadataMap,parentMetadataMap),obj[Symbol.metadata||Symbol.for("Symbol.metadata")]=metadataMap}}function createAddInitializerMethod(initializers){return function(initializer){assertCallable(initializer,"An initializer"),initializers.push(initializer)}}function memberDecCtx(base,name,desc,metadataMap,initializers,kind,isStatic,isPrivate){var kindStr;switch(kind){case 1:kindStr="accessor";break;case 2:kindStr="method";break;case 3:kindStr="getter";break;case 4:kindStr="setter";break;default:kindStr="field"}var metadataKind,metadataName,ctx={kind:kindStr,name:isPrivate?"#"+name:name,isStatic:isStatic,isPrivate:isPrivate};if(0!==kind&&(ctx.addInitializer=createAddInitializerMethod(initializers)),isPrivate){metadataKind=2,metadataName=Symbol(name);var access={};0===kind?(access.get=desc.get,access.set=desc.set):2===kind?access.get=function(){return desc.value}:(1!==kind&&3!==kind||(access.get=function(){return desc.get.call(this)}),1!==kind&&4!==kind||(access.set=function(v){desc.set.call(this,v)})),ctx.access=access}else metadataKind=1,metadataName=name;return Object.assign(ctx,createMetadataMethodsForProperty(metadataMap,metadataKind,metadataName))}function assertCallable(fn,hint){if("function"!=typeof fn)throw new TypeError(hint+" must be a function")}function assertValidReturnValue(kind,value){var type=typeof value;if(1===kind){if("object"!==type||null===value)throw new TypeError("accessor decorators must return an object with get, set, or initializer properties or void 0");void 0!==value.get&&assertCallable(value.get,"accessor.get"),void 0!==value.set&&assertCallable(value.set,"accessor.set"),void 0!==value.initialize&&assertCallable(value.initialize,"accessor.initialize")}else if("function"!==type){var hint;throw hint=0===kind?"field":10===kind?"class":"method",new TypeError(hint+" decorators must return a function or void 0")}}function applyMemberDec(ret,base,decInfo,name,kind,isStatic,isPrivate,metadataMap,initializers){var desc,initializer,value,decs=decInfo[0];isPrivate?desc=0===kind||1===kind?{get:decInfo[3],set:decInfo[4]}:3===kind?{get:decInfo[3]}:4===kind?{set:decInfo[3]}:{value:decInfo[3]}:0!==kind&&(desc=Object.getOwnPropertyDescriptor(base,name)),1===kind?value={get:desc.get,set:desc.set}:2===kind?value=desc.value:3===kind?value=desc.get:4===kind&&(value=desc.set);var newValue,get,set,ctx=memberDecCtx(base,name,desc,metadataMap,initializers,kind,isStatic,isPrivate);if("function"==typeof decs)void 0!==(newValue=decs(value,ctx))&&(assertValidReturnValue(kind,newValue),0===kind?initializer=newValue:1===kind?(initializer=newValue.initialize,get=newValue.get||value.get,set=newValue.set||value.set,value={get:get,set:set}):value=newValue);else for(var i=decs.length-1;i>=0;i--){var newInit;if(void 0!==(newValue=(0,decs[i])(value,ctx)))assertValidReturnValue(kind,newValue),0===kind?newInit=newValue:1===kind?(newInit=newValue.initialize,get=newValue.get||value.get,set=newValue.set||value.set,value={get:get,set:set}):value=newValue,void 0!==newInit&&(void 0===initializer?initializer=newInit:"function"==typeof initializer?initializer=[initializer,newInit]:initializer.push(newInit))}if(0===kind||1===kind){if(void 0===initializer)initializer=function(instance,init){return init};else if("function"!=typeof initializer){var ownInitializers=initializer;initializer=function(instance,init){for(var value=init,i=0;i<ownInitializers.length;i++)value=ownInitializers[i].call(instance,value);return value}}else{var originalInitializer=initializer;initializer=function(instance,init){return originalInitializer.call(instance,init)}}ret.push(initializer)}0!==kind&&(1===kind?(desc.get=value.get,desc.set=value.set):2===kind?desc.value=value:3===kind?desc.get=value:4===kind&&(desc.set=value),isPrivate?1===kind?(ret.push((function(instance,args){return value.get.call(instance,args)})),ret.push((function(instance,args){return value.set.call(instance,args)}))):2===kind?ret.push(value):ret.push((function(instance,args){return value.call(instance,args)})):Object.defineProperty(base,name,desc))}function applyMemberDecs(ret,Class,protoMetadataMap,staticMetadataMap,decInfos){for(var protoInitializers,staticInitializers,existingProtoNonFields=new Map,existingStaticNonFields=new Map,i=0;i<decInfos.length;i++){var decInfo=decInfos[i];if(Array.isArray(decInfo)){var base,metadataMap,initializers,kind=decInfo[1],name=decInfo[2],isPrivate=decInfo.length>3,isStatic=kind>=5;if(isStatic?(base=Class,metadataMap=staticMetadataMap,0!==(kind-=5)&&(initializers=staticInitializers=staticInitializers||[])):(base=Class.prototype,metadataMap=protoMetadataMap,0!==kind&&(initializers=protoInitializers=protoInitializers||[])),0!==kind&&!isPrivate){var existingNonFields=isStatic?existingStaticNonFields:existingProtoNonFields,existingKind=existingNonFields.get(name)||0;if(!0===existingKind||3===existingKind&&4!==kind||4===existingKind&&3!==kind)throw new Error("Attempted to decorate a public method/accessor that has the same name as a previously decorated public method/accessor. This is not currently supported by the decorators plugin. Property name was: "+name);!existingKind&&kind>2?existingNonFields.set(name,kind):existingNonFields.set(name,!0)}applyMemberDec(ret,base,decInfo,name,kind,isStatic,isPrivate,metadataMap,initializers)}}pushInitializers(ret,protoInitializers),pushInitializers(ret,staticInitializers)}function pushInitializers(ret,initializers){initializers&&(initializers.length>0?(initializers=initializers.slice(),ret.push((function(instance){for(var i=0;i<initializers.length;i++)initializers[i].call(instance);return instance}))):ret.push((function(instance){return instance})))}function applyClassDecs(ret,targetClass,metadataMap,classDecs){if(classDecs.length>0){for(var initializers=[],newClass=targetClass,name=targetClass.name,ctx=Object.assign({kind:"class",name:name,addInitializer:createAddInitializerMethod(initializers)},createMetadataMethodsForProperty(metadataMap,0,name)),i=classDecs.length-1;i>=0;i--){var nextNewClass=classDecs[i](newClass,ctx);void 0!==nextNewClass&&(assertValidReturnValue(10,nextNewClass),newClass=nextNewClass)}ret.push(newClass),initializers.length>0?ret.push((function(){for(var i=0;i<initializers.length;i++)initializers[i].call(newClass)})):ret.push((function(){}))}}export default function applyDecs(targetClass,memberDecs,classDecs){var ret=[],staticMetadataMap={},protoMetadataMap={};return applyMemberDecs(ret,targetClass,protoMetadataMap,staticMetadataMap,memberDecs),convertMetadataMapToFinal(targetClass.prototype,protoMetadataMap),applyClassDecs(ret,targetClass,staticMetadataMap,classDecs),convertMetadataMapToFinal(targetClass,staticMetadataMap),ret}',
   ),
   asyncIterator: helper(
     "7.15.9",
diff --git a/packages/babel-helpers/src/helpers/applyDecs.js b/packages/babel-helpers/src/helpers/applyDecs.js
index 76fcae77b812..eddc75641784 100644
--- a/packages/babel-helpers/src/helpers/applyDecs.js
+++ b/packages/babel-helpers/src/helpers/applyDecs.js
@@ -122,7 +122,7 @@ function convertMetadataMapToFinal(obj, metadataMap) {
 
 function createAddInitializerMethod(initializers) {
   return function addInitializer(initializer) {
-    assertCallable(initializer, "initializers");
+    assertCallable(initializer, "An initializer");
     initializers.push(initializer);
   };
 }
@@ -211,7 +211,7 @@ function memberDecCtx(
 
 function assertCallable(fn, hint) {
   if (typeof fn !== "function") {
-    throw new TypeError(hint + " must be functions");
+    throw new TypeError(hint + " must be a function");
   }
 }
 
diff --git a/packages/babel-plugin-proposal-decorators/test/fixtures/2021-12-runtime-errors--to-es2015/invalid-accessor-decorator-return/exec.js b/packages/babel-plugin-proposal-decorators/test/fixtures/2021-12-runtime-errors--to-es2015/invalid-accessor-decorator-return/exec.js
index 11cd09df4176..167c235d3de2 100644
--- a/packages/babel-plugin-proposal-decorators/test/fixtures/2021-12-runtime-errors--to-es2015/invalid-accessor-decorator-return/exec.js
+++ b/packages/babel-plugin-proposal-decorators/test/fixtures/2021-12-runtime-errors--to-es2015/invalid-accessor-decorator-return/exec.js
@@ -11,9 +11,9 @@ const returnsInitializeFalse = () => ({ initialize: false });
 expect(() => class { @returnsNull accessor a }).toThrow("accessor decorators must return an object with get, set, or initializer properties or void 0")
 expect(() => class { @returnsFalse accessor a }).toThrow("accessor decorators must return an object with get, set, or initializer properties or void 0")
 expect(() => class { @returnsFunction accessor a }).toThrow("accessor decorators must return an object with get, set, or initializer properties or void 0")
-expect(() => class { @returnsGetFalse accessor a }).toThrow("accessor.get must be functions");
-expect(() => class { @returnsSetFalse accessor a }).toThrow("accessor.set must be functions");
-expect(() => class { @returnsInitializeFalse accessor a }).toThrow("accessor.initialize must be functions");
+expect(() => class { @returnsGetFalse accessor a }).toThrow("accessor.get must be a function");
+expect(() => class { @returnsSetFalse accessor a }).toThrow("accessor.set must be a function");
+expect(() => class { @returnsInitializeFalse accessor a }).toThrow("accessor.initialize must be a function");
 
 expect(() => class { @returnsGetSet accessor a }).not.toThrow();
 expect(() => class { @returnsInitialize accessor a }).not.toThrow();
diff --git a/packages/babel-plugin-proposal-decorators/test/fixtures/2021-12-runtime-errors--to-es2015/invalid-add-initializer/exec.js b/packages/babel-plugin-proposal-decorators/test/fixtures/2021-12-runtime-errors--to-es2015/invalid-add-initializer/exec.js
new file mode 100644
index 000000000000..a91c771ca9b8
--- /dev/null
+++ b/packages/babel-plugin-proposal-decorators/test/fixtures/2021-12-runtime-errors--to-es2015/invalid-add-initializer/exec.js
@@ -0,0 +1,6 @@
+const decWithInitializer = (init) => (_, context) => { context.addInitializer(init) }
+
+expect(() => class { @decWithInitializer(null) static m() {} }).toThrow("An initializer must be a function")
+expect(() => class { @decWithInitializer(false) static m() {} }).toThrow("An initializer must be a function")
+expect(() => class { @decWithInitializer(void 0) static m() {} }).toThrow("An initializer must be a function");
+expect(() => class { @decWithInitializer(() => {}) static m() {} }).not.toThrow();