Template params can only have one argument

The fact that a promise can also be rejected with a Throwable and/or Exception is implied and there is no need to also define that here.

Refs: reactphp/promise#223

Author: WyriHaximus

src/Browser.php

@@ -344,7 +344,7 @@ public function delete($url, array $headers = array(), $body = '')
      * @param string                         $url      URL for the request
      * @param array                          $headers  Additional request headers
      * @param string|ReadableStreamInterface $body     HTTP request body contents
-     * @return PromiseInterface<ResponseInterface,\Exception>
+     * @return PromiseInterface<ResponseInterface>
      */
     public function request($method, $url, array $headers = array(), $body = '')
     {
@@ -417,7 +417,7 @@ public function request($method, $url, array $headers = array(), $body = '')
      * @param string                         $url      URL for the request
      * @param array                          $headers  Additional request headers
      * @param string|ReadableStreamInterface $body     HTTP request body contents
-     * @return PromiseInterface<ResponseInterface,\Exception>
+     * @return PromiseInterface<ResponseInterface>
      */
     public function requestStreaming($method, $url, $headers = array(), $body = '')
     {
@@ -828,7 +828,7 @@ private function withOptions(array $options)
      * @param string                         $url
      * @param array                          $headers
      * @param string|ReadableStreamInterface $body
-     * @return PromiseInterface<ResponseInterface,\Exception>
+     * @return PromiseInterface<ResponseInterface>
      */
     private function requestMayBeStreaming($method, $url, array $headers = array(), $body = '')
     {