Add improved exception handling

src/Provider/Exception/GithubIdentityProviderException.php

@@ -0,0 +1,53 @@
+<?php
+
+namespace League\OAuth2\Client\Provider\Exception;
+
+use Psr\Http\Message\ResponseInterface;
+
+class GithubIdentityProviderException extends IdentityProviderException
+{
+    /**
+     * Creates client exception from response.
+     *
+     * @param  ResponseInterface $response
+     * @param  string $data Parsed response data
+     *
+     * @return IdentityProviderException
+     */
+    public static function clientException(ResponseInterface $response, $data)
+    {
+        return static::fromResponse(
+            $response,
+            isset($data['message']) ? $data['message'] : $response->getReasonPhrase()
+        );
+    }
+
+    /**
+     * Creates oauth exception from response.
+     *
+     * @param  ResponseInterface $response
+     * @param  string $data Parsed response data
+     *
+     * @return IdentityProviderException
+     */
+    public static function oauthException(ResponseInterface $response, $data)
+    {
+        return static::fromResponse(
+            $response,
+            isset($data['error']) ? $data['error'] : $response->getReasonPhrase()
+        );
+    }
+
+    /**
+     * Creates identity exception from response.
+     *
+     * @param  ResponseInterface $response
+     * @param  string $message
+     *
+     * @return IdentityProviderException
+     */
+    protected static function fromResponse(ResponseInterface $response, $message = null)
+    {
+        return new static($message, $response->getStatusCode(), (string) $response->getBody());
+    }
+}

src/Provider/Github.php

@@ -2,7 +2,7 @@
 
 namespace League\OAuth2\Client\Provider;
 
-use League\OAuth2\Client\Provider\Exception\IdentityProviderException;
+use League\OAuth2\Client\Provider\Exception\GithubIdentityProviderException;
 use League\OAuth2\Client\Token\AccessToken;
 use League\OAuth2\Client\Tool\BearerAuthorizationTrait;
 use Psr\Http\Message\ResponseInterface;
@@ -79,6 +79,7 @@ protected function getDefaultScopes()
      * Check a provider response for errors.
      *
      * @link   https://developer.github.com/v3/#client-errors
+     * @link   https://developer.github.com/v3/oauth/#common-errors-for-the-access-token-request
      * @throws IdentityProviderException
      * @param  ResponseInterface $response
      * @param  string $data Parsed response data
@@ -87,11 +88,9 @@ protected function getDefaultScopes()
     protected function checkResponse(ResponseInterface $response, $data)
     {
         if ($response->getStatusCode() >= 400) {
-            $errorMessage = isset($data['message']) ? $data['message'] : $response->getReasonPhrase();
-            throw new IdentityProviderException($errorMessage, $response->getStatusCode(), $response);
-        } elseif (isset($data['error'], $data['error_description'])) {
-            $errorMessage = $data['error'] . ': ' . $data['error_description'];
-            throw new IdentityProviderException($errorMessage, $response->getStatusCode(), $response);
+            throw GithubIdentityProviderException::clientException($response, $data);
+        } elseif (isset($data['error'])) {
+            throw GithubIdentityProviderException::oauthException($response, $data);
         }
     }