[gnome-shell] workspacesView: Check for primaryView being null

[Marge Bot <marge-bot src gnome org>]

commit a498d8577ec2e0564f7ee322f6de6216d824e8fc
Author: Carlos Garnacho <carlosg gnome org>
Date:   Mon Jan 4 17:42:26 2021 +0100

    workspacesView: Check for primaryView being null
    
    This is possible according to the getter, and triggers warnings
    seen when going back from overview via gestures.
    
    Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1643>

 js/ui/workspacesView.js | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
---
diff --git a/js/ui/workspacesView.js b/js/ui/workspacesView.js
index 177fd413d9..268adae44c 100644
--- a/js/ui/workspacesView.js
+++ b/js/ui/workspacesView.js
@@ -873,7 +873,10 @@ class WorkspacesDisplay extends St.Widget {
     }
 
     activeWorkspaceHasMaximizedWindows() {
-        return this._getPrimaryView().getActiveWorkspace().hasMaximizedWindows();
+        const primaryView = this._getPrimaryView();
+        return primaryView
+            ? primaryView.getActiveWorkspace().hasMaximizedWindows()
+            : false;
     }
 
     _onRestacked(overview, stackIndices) {