Update handler.py

handler.py

@@ -141,9 +141,12 @@ class Transcript:
                 utt.role = 'student'
                 student_words += utt.get_num_words()
                 student_utt_count += 1
-        teacher_percentage = round(
-            (teacher_words / (teacher_words + student_words)) * 100)
-        student_percentage = 100 - teacher_percentage
+        if teacher_words + student_words > 0:         
+            teacher_percentage = round(
+                (teacher_words / (teacher_words + student_words)) * 100)
+            student_percentage = 100 - teacher_percentage
+        else:
+            teacher_percentage = student_percentage = 0
         avg_teacher_length = teacher_words / teacher_utt_count if teacher_utt_count > 0 else 0
         avg_student_length = student_words / student_utt_count if student_utt_count > 0 else 0
         return {'teacher': teacher_percentage, 'student': student_percentage}, {'teacher': avg_teacher_length, 'student': avg_student_length}