add base case check if any parameters are empty (return two empty strings)

app.py

@@ -75,6 +75,8 @@ def clean_json_string(json_str):
     return json_str
 
 def model_call(question, document, answer):
+    if question === "" or document === "" or answer === "":
+        return "", ""
     NEW_FORMAT = PROMPT.format(question=question, document=document, answer=answer)
     print("ENTIRE NEW_FORMAT", NEW_FORMAT)
     response = client.completions.create(