Fix error after leaving team (#4888)

webapp/actions/websocket_actions.jsx

@@ -223,6 +223,7 @@ function handleLeaveTeamEvent(msg) {
         if (TeamStore.getCurrentId() === msg.data.team_id) {
             TeamStore.setCurrentId('');
             Client.setTeamId('');
+            BrowserStore.removeGlobalItem('team');
             BrowserStore.removeGlobalItem(msg.data.team_id);
             GlobalActions.redirectUserToDefaultTeam();
         }

webapp/utils/async_client.jsx

@@ -139,7 +139,7 @@ export function getMyChannelMembers() {
 }
 
 export function viewChannel(channelId = ChannelStore.getCurrentId(), prevChannelId = '', time = 0) {
-    if (channelId == null) {
+    if (channelId == null || !Client.teamId) {
         return;
     }