Fixes for admins when LastBoardID doesn't exist (#22993)

* fixes for admins when LastBoardID doesn't exist

* lint fixes

* Update webapp/boards/src/components/sidebar/sidebarCategory.tsx

Co-authored-by: Caleb Roseland <caleb@calebroseland.com>

* after deletion, if no boards, send to team (template selector)

---------

Co-authored-by: Caleb Roseland <caleb@calebroseland.com>
Co-authored-by: Mattermost Build <build@mattermost.com>

webapp/boards/src/components/sidebar/sidebarCategory.tsx

@@ -25,6 +25,7 @@ import CompassIcon from 'src/widgets/icons/compassIcon'
 import OptionsIcon from 'src/widgets/icons/options'
 import Menu from 'src/widgets/menu'
 import MenuWrapper from 'src/widgets/menuWrapper'
+import {UserSettings} from 'src/userSettings'
 
 import './sidebarCategory.scss'
 import {Category, CategoryBoardMetadata, CategoryBoards} from 'src/store/sidebar'
@@ -202,12 +203,24 @@ const SidebarCategory = (props: Props) => {
                     setTimeout(() => {
                         showBoard(props.boards[nextBoardId as number].id)
                     }, 120)
+                } else {
+                    setTimeout(() => {
+                        const newPath = generatePath('/team/:teamId', {teamId: teamID,})
+                        history.push(newPath)
+                    }, 120)
                 }
             },
             async () => {
                 showBoard(deleteBoard.id)
             },
         )
+        if (
+            UserSettings.lastBoardId && 
+            UserSettings.lastBoardId[deleteBoard.teamId] == deleteBoard.id
+        ) {
+            UserSettings.setLastBoardID(deleteBoard.teamId, null)
+            UserSettings.setLastViewId(deleteBoard.id, null)
+        }
     }, [showBoard, deleteBoard, props.boards])
 
     const updateCategory = useCallback(async (value: boolean) => {

webapp/boards/src/pages/boardPage/boardPage.tsx

@@ -186,7 +186,9 @@ const BoardPage = (props: Props): JSX.Element => {
     const joinBoard = async (myUser: IUser, boardTeamId: string, boardId: string, allowAdmin: boolean) => {
         const member = await octoClient.joinBoard(boardId, allowAdmin)
         if (!member) {
-            if (myUser.permissions?.find((s) => s === 'manage_system' || s === 'manage_team')) {
+            // if allowAdmin is true, then we failed to join the board
+            // as an admin, normally, this is deleted/missing board
+            if (!allowAdmin && myUser.permissions?.find((s) => s === 'manage_system' || s === 'manage_team')) {
                 setShowJoinBoardDialog(true)
                 return
             }