raise excpetion in case of invalid keys

Author: toto

Sources/OAuth2Client/NXOAuth2Client.m

@@ -121,7 +121,11 @@ - (void)setAdditionalAuthenticationParameters:(NSDictionary *)value;
                                 @"assertion_type", @"assertion" ];
 
     for (id key in value) {
-        NSAssert1([forbiddenKeys containsObject:key] == NO, @"The key %@ may not be used in additionalAuthenticationParameters", key);
+        if ([forbiddenKeys containsObject:key]) {
+            [[NSException exceptionWithName:NSInvalidArgumentException
+                                     reason:[NSString stringWithFormat:@"'%@' is not allowed as a key for additionalAuthenticationParameters", key]
+                                   userInfo:nil] raise];
+        }
     }
 
     additionalAuthenticationParameters = value;