### Expected behavior No error occurs when `spreadArray` is used on a string containing an emoji/Unicode character. ### Current behavior When `spreadArray` is used on a string containing an emoji/Unicode character, the following error occurs: ``` TypeError: Cannot use 'in' operator to search for '0' in ❤️ at __spreadArray ``` I believe the problem is related to https://github.com/microsoft/tslib/blob/2.3.1/tslib.js#L208 because if you run ... ```js '0' in '❤️'; // ... or ... __spreadArray([], "❤️", true); ``` ... the same error occurs. ### Steps to reproduce https://codesandbox.io/s/beautiful-cohen-86fygb?file=/src/index.js:220-251 ### Context I need to replace some emojis with images so I am using [emoji-regex](https://github.com/mathiasbynens/emoji-regex) to find them and get the true length of the emoji so that it can be substituted, they recommend using ... ```js [...emoji].length ``` ... that under certain `tsconfig.json` options, will be transpiled to ... ```js __spreadArray([], emoji, true).length ``` I have tried other variations, including `Array.from()` and `emoji.length`, and only the variation above yields accurate lengths. Fortunately, swallowing the error in a `try-catch` seems to work so it seems the error is not critical for `spreadArray` to function for some reason and I do not know why.