Only throw factorial-related exception on factorial raised exception

common/lib/capa/capa/responsetypes.py

@@ -1852,12 +1852,18 @@ class FormulaResponse(LoncapaResponse):
                 raise StudentInputError(
                     "Invalid input: " + uv.message + " not permitted in answer")
             except ValueError as ve:
+                if 'factorial' in ve.message:
                     # This is thrown when fact() or factorial() is used in a formularesponse answer
                     #   that tests on negative and/or non-integer inputs
+                    # ve.message will be: `factorial() only accepts integral values` or `factorial() not defined for negative values`
                     log.debug(
                         'formularesponse: factorial function used in response that tests negative and/or non-integer inputs. given={0}'.format(given))
                     raise StudentInputError(
                         "factorial function not permitted in answer for this problem. Provided answer was: {0}".format(given))
+                # If non-factorial related ValueError thrown, handle it the same as any other Exception
+                log.debug('formularesponse: error {0} in formula'.format(ve))
+                raise StudentInputError("Invalid input: Could not parse '%s' as a formula" %
+                                        cgi.escape(given))
             except Exception as err:
                 # traceback.print_exc()
                 log.debug('formularesponse: error %s in formula' % err)