Set type of `store` argument to groups service

This found a mistake in the types of several references to the document
URI, which is not always present.

src/sidebar/helpers/groups.js

@@ -33,7 +33,7 @@ function allowLeavingGroups(settings) {
  *
  * @param {Group[]} userGroups - groups the user is a member of
  * @param {Group[]} featuredGroups - all other groups, may include some duplicates from the userGroups
- * @param {string} uri - uri of the current page
+ * @param {string|null} uri - uri of the current page
  * @param {HostConfig} settings
  */
 export function combineGroups(userGroups, featuredGroups, uri, settings) {
@@ -69,7 +69,7 @@ export function combineGroups(userGroups, featuredGroups, uri, settings) {
 
 /**
  * @param {Group} group
- * @param {string} uri
+ * @param {string|null} uri
  */
 function isScopedToUri(group, uri) {
   /* If a scope check cannot be performed, meaning:

src/sidebar/services/groups.js

@@ -21,6 +21,7 @@ const DEFAULT_ORGANIZATION = {
 };
 
 /**
+ * @param {import('../store').SidebarStore} store
  * @param {import('./toast-messenger').ToastMessengerService} toastMessenger
  * @param {import('./auth').AuthService} auth
  */
@@ -218,7 +219,7 @@ export default function groups(
   async function loadGroupsForUserAndDocument() {
     // Step 1: Get the URI of the active document, so we can fetch groups
     // associated with that document.
-    let documentUri;
+    let documentUri = null;
     if (store.route() === 'sidebar') {
       documentUri = await getDocumentUriForGroupSearch();
     }