Grabbed dndbeyond's source code

```
~/go/bin/sourcemapper -output ddb -jsurl https://media.dndbeyond.com/character-app/static/js/main.90aa78c5.js
```

ddb_main/node_modules/@mui/utils/getValidReactChildren/getValidReactChildren.js

@@ -0,0 +1,11 @@
+import * as React from 'react';
+
+/**
+ * Gets only the valid children of a component,
+ * and ignores any nullish or falsy child.
+ *
+ * @param children the children
+ */
+export default function getValidReactChildren(children) {
+  return React.Children.toArray(children).filter(child => /*#__PURE__*/React.isValidElement(child));
+}