[orca] Return an empty list when generate current line text fails to obtain a result

[Joanmarie Diggs <joanied src gnome org>]

commit 56858aeec9b61c5eaa82cbe17909e398fee9c65f
Author: Joanmarie Diggs <jdiggs igalia com>
Date:   Wed Jul 3 13:10:07 2019 -0400

    Return an empty list when generate current line text fails to obtain a result

 src/orca/speech_generator.py | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)
---
diff --git a/src/orca/speech_generator.py b/src/orca/speech_generator.py
index f1e4a7b56..a96d6c04d 100644
--- a/src/orca/speech_generator.py
+++ b/src/orca/speech_generator.py
@@ -984,16 +984,19 @@ class SpeechGenerator(generator.Generator):
         """
 
         result = self._generateSubstring(obj, **args)
-        if result:
+        if result and result[0]:
             return result
 
         acss = self.voice(DEFAULT)
         result = generator.Generator._generateCurrentLineText(self, obj, **args)
-        if result:
-            if result == ['\n'] and _settingsManager.getSetting('speakBlankLines') \
-               and not self._script.inSayAll() and args.get('total', 1) == 1:
-                result = [messages.BLANK]
-            result.extend(acss)
+        if not (result and result[0]):
+            return []
+
+        if result == ['\n'] and _settingsManager.getSetting('speakBlankLines') \
+           and not self._script.inSayAll() and args.get('total', 1) == 1:
+            result = [messages.BLANK]
+
+        result.extend(acss)
         return result
 
     def _generateDisplayedText(self, obj, **args):