Fix follow request notifications (#15048)

app/javascript/mastodon/reducers/user_lists.js

@@ -53,14 +53,20 @@ import {
 } from 'mastodon/actions/directory';
 import { Map as ImmutableMap, List as ImmutableList } from 'immutable';
 
+const initialListState = ImmutableMap({
+  next: null,
+  isLoading: false,
+  items: ImmutableList(),
+});
+
 const initialState = ImmutableMap({
-  followers: ImmutableMap(),
-  following: ImmutableMap(),
-  reblogged_by: ImmutableMap(),
-  favourited_by: ImmutableMap(),
-  follow_requests: ImmutableMap(),
-  blocks: ImmutableMap(),
-  mutes: ImmutableMap(),
+  followers: initialListState,
+  following: initialListState,
+  reblogged_by: initialListState,
+  favourited_by: initialListState,
+  follow_requests: initialListState,
+  blocks: initialListState,
+  mutes: initialListState,
 });
 
 const normalizeList = (state, path, accounts, next) => {