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/system/esm/useTheme.js

@@ -0,0 +1,9 @@
+'use client';
+
+import createTheme from './createTheme';
+import useThemeWithoutDefault from './useThemeWithoutDefault';
+export const systemDefaultTheme = createTheme();
+function useTheme(defaultTheme = systemDefaultTheme) {
+  return useThemeWithoutDefault(defaultTheme);
+}
+export default useTheme;