Grabbed dndbeyond's source code

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

ddb_main/tools/js/CharacterSheet/reducers/sheet.ts

@@ -0,0 +1,24 @@
+import { SheetAction, sheetActionTypes } from "../actions/sheet";
+import { SheetState } from "../typings";
+
+const initialState: SheetState = {
+  initFailed: false,
+  initError: null,
+};
+function sheet(
+  state: SheetState = initialState,
+  action: SheetAction
+): SheetState {
+  switch (action.type) {
+    case sheetActionTypes.CHARACTER_RECEIVE_FAIL:
+      return {
+        ...state,
+        initFailed: true,
+        initError: action.payload.error,
+      };
+  }
+
+  return state;
+}
+
+export default sheet;