diff --git a/packages/babel-traverse/src/path/family.ts b/packages/babel-traverse/src/path/family.ts
index 0e38ec28a751..6b49758ba489 100644
--- a/packages/babel-traverse/src/path/family.ts
+++ b/packages/babel-traverse/src/path/family.ts
@@ -231,29 +231,25 @@ function _getCompletionRecords(
     path.isLabeledStatement()
   ) {
     // @ts-expect-error(flow->ts): todo
-    records = addCompletionRecords(path.get("body"), records, context);
+    return addCompletionRecords(path.get("body"), records, context);
   } else if (path.isProgram() || path.isBlockStatement()) {
-    records.push(
-      // @ts-expect-error(flow->ts): todo
-      ...getStatementListCompletion(path.get("body"), context),
-    );
+    // @ts-expect-error(flow->ts): todo
+    return getStatementListCompletion(path.get("body"), context);
   } else if (path.isFunction()) {
     return _getCompletionRecords(path.get("body"), context);
   } else if (path.isTryStatement()) {
     records = addCompletionRecords(path.get("block"), records, context);
     records = addCompletionRecords(path.get("handler"), records, context);
   } else if (path.isCatchClause()) {
-    records = addCompletionRecords(path.get("body"), records, context);
+    return addCompletionRecords(path.get("body"), records, context);
   } else if (path.isSwitchStatement()) {
-    records = completionRecordForSwitch(path.get("cases"), records, context);
+    return completionRecordForSwitch(path.get("cases"), records, context);
   } else if (path.isSwitchCase()) {
-    records.push(
-      ...getStatementListCompletion(path.get("consequent"), {
-        canHaveBreak: true,
-        shouldPopulateBreak: false,
-        inCaseClause: true,
-      }),
-    );
+    return getStatementListCompletion(path.get("consequent"), {
+      canHaveBreak: true,
+      shouldPopulateBreak: false,
+      inCaseClause: true,
+    });
   } else if (path.isBreakStatement()) {
     records.push(BreakCompletion(path));
   } else {
diff --git a/packages/babel-types/src/modifications/flow/removeTypeDuplicates.ts b/packages/babel-types/src/modifications/flow/removeTypeDuplicates.ts
index 90d8ba233a17..b57d62e0eec1 100644
--- a/packages/babel-types/src/modifications/flow/removeTypeDuplicates.ts
+++ b/packages/babel-types/src/modifications/flow/removeTypeDuplicates.ts
@@ -17,7 +17,8 @@ function getQualifiedName(node: t.GenericTypeAnnotation["id"]) {
  * Dedupe type annotations.
  */
 export default function removeTypeDuplicates(
-  nodes: (t.FlowType | false | null | undefined)[],
+  // todo(babel-8): change type to Array<...>
+  nodes: ReadonlyArray<t.FlowType | false | null | undefined>,
 ): t.FlowType[] {
   const generics = {};
   const bases = {};
@@ -48,7 +49,8 @@ export default function removeTypeDuplicates(
 
     if (isUnionTypeAnnotation(node)) {
       if (typeGroups.indexOf(node.types) < 0) {
-        nodes.push(...node.types);
+        // todo(babel-8): remove type casting
+        (nodes as any).push(...node.types);
         typeGroups.push(node.types);
       }
       continue;