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/createChainedFunction/createChainedFunction.js

@@ -0,0 +1,17 @@
+/**
+ * Safe chained function.
+ *
+ * Will only create a new function if needed,
+ * otherwise will pass back existing functions or null.
+ */
+export default function createChainedFunction(...funcs) {
+  return funcs.reduce((acc, func) => {
+    if (func == null) {
+      return acc;
+    }
+    return function chainedFunction(...args) {
+      acc.apply(this, args);
+      func.apply(this, args);
+    };
+  }, () => {});
+}