Improve Content-Type handling in exception handling code

Author: oschwald

HISTORY.rst

@@ -3,6 +3,13 @@
 History
 -------
 
+2.7.2 (2022-03-29)
+++++++++++++++++++
+
+* Updated code to correctly handle ``None`` ``Content-Type`` from minFraud
+  web service. This should never happen, but if it does, the correct
+  exception will now be thrown.
+
 2.7.1 (2022-03-29)
 ++++++++++++++++++
 

minfraud/webservice.py

@@ -83,7 +83,7 @@ def _handle_success(
         return model_class(decoded_body)  # type: ignore
 
     def _exception_for_error(
-        self, status: int, content_type: str, raw_body: str, uri: str
+        self, status: int, content_type: Optional[str], raw_body: str, uri: str
     ) -> Union[
         AuthenticationError,
         InsufficientFundsError,
@@ -100,7 +100,7 @@ def _exception_for_error(
         return self._exception_for_unexpected_status(status, raw_body, uri)
 
     def _exception_for_4xx_status(
-        self, status: int, content_type: str, raw_body: str, uri: str
+        self, status: int, content_type: Optional[str], raw_body: str, uri: str
     ) -> Union[
         AuthenticationError,
         InsufficientFundsError,
@@ -113,7 +113,7 @@ def _exception_for_4xx_status(
             return HTTPError(
                 f"Received a {status} error with no body", status, uri, raw_body
             )
-        if content_type.find("json") == -1:
+        if content_type is None or content_type.find("json") == -1:
             return HTTPError(
                 f"Received a {status} with the following body: {raw_body}",
                 status,