fix destructuring of empty string

packages/babel-helpers/src/helpers.js

@@ -903,7 +903,7 @@ helpers.iterableToArrayLimit = helper("7.0.0-beta.0")`
     // _i = _iterator
     // _s = _step
 
-    var _i = arr && (typeof Symbol !== "undefined" && arr[Symbol.iterator] || arr["@@iterator"]);
+    var _i = arr == null ? null : (typeof Symbol !== "undefined" && arr[Symbol.iterator] || arr["@@iterator"]);
     if (_i == null) return;
 
     var _arr = [];

packages/babel-plugin-transform-destructuring/test/fixtures/destructuring/empty-string/exec.js

@@ -0,0 +1,3 @@
+let [a] = '';
+
+expect(a).toBe(undefined)

packages/babel-plugin-transform-destructuring/test/fixtures/destructuring/empty-string/input.js

@@ -0,0 +1 @@
+let [a] = '';

packages/babel-plugin-transform-destructuring/test/fixtures/destructuring/empty-string/output.js

@@ -0,0 +1,3 @@
+var _ref = '',
+    _ref2 = babelHelpers.slicedToArray(_ref, 1),
+    a = _ref2[0];

packages/babel-plugin-transform-modules-commonjs/test/fixtures/regression/T7199/output.js

@@ -12,7 +12,7 @@ function _unsupportedIterableToArray(o, minLen) { if (!o) return; if (typeof o =
 
 function _arrayLikeToArray(arr, len) { if (len == null || len > arr.length) len = arr.length; for (var i = 0, arr2 = new Array(len); i < len; i++) arr2[i] = arr[i]; return arr2; }
 
-function _iterableToArrayLimit(arr, i) { var _i = arr && (typeof Symbol !== "undefined" && arr[Symbol.iterator] || arr["@@iterator"]); if (_i == null) return; var _arr = []; var _n = true; var _d = false; var _s, _e; try { for (_i = _i.call(arr); !(_n = (_s = _i.next()).done); _n = true) { _arr.push(_s.value); if (i && _arr.length === i) break; } } catch (err) { _d = true; _e = err; } finally { try { if (!_n && _i["return"] != null) _i["return"](); } finally { if (_d) throw _e; } } return _arr; }
+function _iterableToArrayLimit(arr, i) { var _i = arr == null ? null : typeof Symbol !== "undefined" && arr[Symbol.iterator] || arr["@@iterator"]; if (_i == null) return; var _arr = []; var _n = true; var _d = false; var _s, _e; try { for (_i = _i.call(arr); !(_n = (_s = _i.next()).done); _n = true) { _arr.push(_s.value); if (i && _arr.length === i) break; } } catch (err) { _d = true; _e = err; } finally { try { if (!_n && _i["return"] != null) _i["return"](); } finally { if (_d) throw _e; } } return _arr; }
 
 function _arrayWithHoles(arr) { if (Array.isArray(arr)) return arr; }
 

yarn.lock

@@ -658,6 +658,7 @@ __metadata:
   resolution: "@babel/helper-module-transforms@condition:BABEL_8_BREAKING?:workspace:^7.14.5#2510a1"
   dependencies:
     "@babel/helper-module-transforms-BABEL_8_BREAKING-false": "npm:@babel/helper-module-transforms@workspace:^7.14.5"
+  checksum: eb4895913562bf398b8bf7e6c68a0380f153f52f2715b3685f9d07e376725227678c2f920dfe0772012dfed655e037534619de86bb9f3284b92555f8bf9d0f42
   languageName: node
   linkType: hard