[orca] Fix for a traceback when Thunderbird becomes unresponsive

[Joanmarie Diggs <joanied src gnome org>]

commit 4af1b4e9b2a77c29e999ad8d87b470f031bd93f4
Author: Joanmarie Diggs <jdiggs igalia com>
Date:   Fri Nov 22 15:58:48 2013 -0500

    Fix for a traceback when Thunderbird becomes unresponsive

 src/orca/script_utilities.py |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)
---
diff --git a/src/orca/script_utilities.py b/src/orca/script_utilities.py
index 27adc76..470c147 100644
--- a/src/orca/script_utilities.py
+++ b/src/orca/script_utilities.py
@@ -1778,7 +1778,11 @@ class Utilities:
         Returns the fully expanded text for the object.
         """
 
-        string = self.substring(obj, startOffset, endOffset)
+        try:
+            string = self.substring(obj, startOffset, endOffset)
+        except:
+            return ""
+
         if self.EMBEDDED_OBJECT_CHARACTER in string:
             # If we're not getting the full text of this object, but
             # rather a substring, we need to figure out the offset of