Correct max position for SQUAD and TFDS

transformers/data/processors/squad.py

@@ -571,7 +571,9 @@ class SquadExample(object):
         # Start end end positions only has a value during evaluation.
         if start_position_character is not None and not is_impossible:
             self.start_position = char_to_word_offset[start_position_character]
-            self.end_position = char_to_word_offset[start_position_character + len(answer_text) - 1]
+            self.end_position = char_to_word_offset[
+                min(start_position_character + len(answer_text) - 1, len(char_to_word_offset) - 1)
+            ]
 
 
 class SquadFeatures(object):