Merge branch 'ss/fix-board-error' into 'master'

Provide default to epics_select/base.vue

See merge request gitlab-org/gitlab!44096

app/assets/javascripts/boards/index.js

@@ -84,7 +84,7 @@ export default () => {
     },
     provide: {
       boardId: $boardApp.dataset.boardId,
-      groupId: Number($boardApp.dataset.groupId) || null,
+      groupId: Number($boardApp.dataset.groupId),
       rootPath: $boardApp.dataset.rootPath,
       canUpdate: $boardApp.dataset.canUpdate,
     },