Update attributeManager.py

src/fenrirscreenreader/core/attributeManager.py

@@ -9,6 +9,8 @@ from collections import Counter
 
 class attributeManager():
     def __init__(self):
+        self.currAttributes = None
+        self.prevAttributes = None
         self.setDefaultAttributes()        
     def initialize(self, environment):
         self.env = environment  
@@ -165,6 +167,9 @@ class attributeManager():
         # no change
         if oldAttr == newAttr:
             return result,  currCursor
+        # error case
+        if newAttr == None:
+            return result,  currCursor                  
         # special case for pty if not text exists.
         if len(newAttr) == 0:
             return result,  currCursor