[orca] Handle exception initializing mouse review with null display

[Joanmarie Diggs <joanied src gnome org>]

commit abd79ae9069f5d9448fb1325576aa82b0bed4158
Author: Joanmarie Diggs <jdiggs igalia com>
Date:   Tue Dec 15 11:52:43 2020 +0100

    Handle exception initializing mouse review with null display

 src/orca/mouse_review.py | 4 ++++
 1 file changed, 4 insertions(+)
---
diff --git a/src/orca/mouse_review.py b/src/orca/mouse_review.py
index 0bafd9487..6f1d53b8f 100644
--- a/src/orca/mouse_review.py
+++ b/src/orca/mouse_review.py
@@ -342,6 +342,10 @@ class MouseReviewer:
             msg = "MOUSE REVIEW ERROR: Gtk+ 3.20 is not available"
             debug.println(debug.LEVEL_INFO, msg, True)
             return
+        except:
+            msg = "MOUSE REVIEW ERROR: Exception getting pointer for default seat."
+            debug.println(debug.LEVEL_INFO, msg, True)
+            return
 
         if not self._active:
             return