• File “/usr/local/lib/python3. 9/site-packages/flask/app. py”, line 2548, in __call__

   def __call__(self, environ: dict, start_response: t. Callable) -> t. Any:

   """The WSGI server calls the Flask application object as the

   WSGI application. This calls :meth:'wsgi_app', which can be

   wrapped to apply middleware. 

   """

   return self. wsgi_app(environ, start_response)

• File “/usr/local/lib/python3. 9/site-packages/flask/app. py”, line 2528, in wsgi_app

   try:

   ctx. push()

   response = self. full_dispatch_request()

   except Exception as e:

   error = e

   response = self. handle_exception(e)

   except: # noqa: B001

   error = sys. exc_info()[1]

   raise

   return response(environ, start_response)

   finally:

• File “/usr/local/lib/python3. 9/site-packages/flask/app. py”, line 2525, in wsgi_app

   ctx = self. request_context(environ)

   error: t. Optional[BaseException] = None

   try:

   try:

   ctx. push()

   response = self. full_dispatch_request()

   except Exception as e:

   error = e

   response = self. handle_exception(e)

   except: # noqa: B001

   error = sys. exc_info()[1]

• File “/usr/local/lib/python3. 9/site-packages/flask/app. py”, line 1822, in full_dispatch_request

   request_started. send(self)

   rv = self. preprocess_request()

   if rv is None:

   rv = self. dispatch_request()

   except Exception as e:

   rv = self. handle_user_exception(e)

   return self. finalize_request(rv)

   def finalize_request(

   self,

   rv: t. Union[ft. ResponseReturnValue, HTTPException],

• File “/usr/local/lib/python3. 9/site-packages/flask/app. py”, line 1820, in full_dispatch_request

   try:

   request_started. send(self)

   rv = self. preprocess_request()

   if rv is None:

   rv = self. dispatch_request()

   except Exception as e:

   rv = self. handle_user_exception(e)

   return self. finalize_request(rv)

   def finalize_request(

• File “/usr/local/lib/python3. 9/site-packages/flask/app. py”, line 1796, in dispatch_request

   and req. method == "OPTIONS"

   ):

   return self. make_default_options_response()

   # otherwise dispatch to the handler for that endpoint

   view_args: t. Dict[str, t. Any] = req. view_args # type: ignore[assignment]

   return self. ensure_sync(self. view_functions[rule. endpoint])(**view_args)

   def full_dispatch_request(self) -> Response:

   """Dispatches the request and on top of that performs request

   pre and postprocessing as well as HTTP exception catching and

   error handling. 

• File “/nlpapps/app. py”, line 462, in process_summarytext

   sentence_list = nltk. sent_tokenize(article_text)

  # Find the weighted frequency

   maximum_frequncy = max(word_frequencies. values())

   for word in word_frequencies. keys():

   word_frequencies[word] = (word_frequencies[word]/maximum_frequncy)

  # Calculate sentence scores

ValueError: max() arg is an empty sequence