Applied [patch](nxtbgthng#80) from @kangaroo5383

Author: Gavin Koehler

.gitignore

@@ -16,3 +16,4 @@ profile
 *.moved-aside
 DerivedData
 .idea/
+*.patch

Sources/OAuth2Client/NXOAuth2Client.m

@@ -499,6 +499,12 @@ - (void)oauthConnection:(NXOAuth2Connection *)connection didFailWithError:(NSErr
     NSString *body = [[NSString alloc] initWithData:connection.data encoding:NSUTF8StringEncoding];
     NSLog(@"oauthConnection Error: %@", body);
 
+    NSMutableDictionary *userInfo = [NSMutableDictionary dictionaryWithDictionary:error.userInfo];
+    if (connection.data) {
+        [userInfo setObject:connection.data forKey:NXOAuth2ErrorResponseDataKey];
+    }
+    
+    NSError *updatedError = [NSError errorWithDomain:error.domain code:error.code userInfo:[NSDictionary dictionaryWithDictionary:userInfo]];
 
     if (connection == authConnection) {
         self.authenticating = NO;
@@ -539,7 +545,7 @@ - (void)oauthConnection:(NXOAuth2Connection *)connection didFailWithError:(NSErr
             }
 
             if ([delegate respondsToSelector:@selector(oauthClient:didFailToGetAccessTokenWithError:)]) {
-                [delegate oauthClient:self didFailToGetAccessTokenWithError:error];
+                [delegate oauthClient:self didFailToGetAccessTokenWithError:updatedError];
             }
         }
     }

Sources/OAuth2Client/NXOAuth2Constants.h

@@ -106,4 +106,4 @@ typedef enum  {
 
 
 extern NSString * const NXOAuth2AccountStoreErrorKey;
-
+extern NSString * const NXOAuth2ErrorResponseDataKey;

Sources/OAuth2Client/NXOAuth2Constants.m

@@ -38,3 +38,4 @@
 #pragma mark UserInfo Keys
 
 NSString * const NXOAuth2AccountStoreErrorKey = @"NXOAuth2AccountStoreErrorKey";
+NSString * const NXOAuth2ErrorResponseDataKey = @"NXOAuth2ErrorResponseDataKey";