[orca] Handle exception checking interfaces on null table cell

[Joanmarie Diggs <joanied src gnome org>]

commit dd65e0ea3d75ebe3df96cde3847ddf5df7f3ff74
Author: Joanmarie Diggs <jdiggs igalia com>
Date:   Tue Oct 11 14:39:30 2022 +0200

    Handle exception checking interfaces on null table cell
    
    Fixes recent regression presenting newly-edited calc cell

 src/orca/script_utilities.py | 10 ++++++++++
 1 file changed, 10 insertions(+)
---
diff --git a/src/orca/script_utilities.py b/src/orca/script_utilities.py
index 2a3a1952c..4aa7fb194 100644
--- a/src/orca/script_utilities.py
+++ b/src/orca/script_utilities.py
@@ -4492,6 +4492,11 @@ class Utilities:
         return result
 
     def _columnHeadersForCell(self, obj):
+        if not obj:
+            msg = "INFO: Attempted to get column headers for null cell"
+            debug.println(debug.LEVEL_INFO, msg, True)
+            return []
+
         if 'TableCell' in pyatspi.listInterfaces(obj):
             tableCell = obj.queryTableCell()
             try:
@@ -4532,6 +4537,11 @@ class Utilities:
         return result
 
     def _rowHeadersForCell(self, obj):
+        if not obj:
+            msg = "INFO: Attempted to get row headers for null cell"
+            debug.println(debug.LEVEL_INFO, msg, True)
+            return []
+
         if 'TableCell' in pyatspi.listInterfaces(obj):
             tableCell = obj.queryTableCell()
             try: