updated bundles process

app/lib/irt/item_response_function.py

@@ -1,4 +1,5 @@
 from lib.irt.models.three_parameter_logistic import ThreeParameterLogistic
+from lib.errors.item_generation_error import ItemGenerationError
 
 class ItemResponseFunction():
   def __init__(self, irt_model):
@@ -8,5 +9,4 @@ class ItemResponseFunction():
     if self.model_data.model == '3PL':
       return ThreeParameterLogistic(self.model_data, kwargs).result()
     else:
-      # potentially error out
-      return None
+      raise ItemGenerationError("irt model not supported or provided")