Merge pull request #118 from async-interop/return_old_error_handler

Loop::setErrorHandler should return the last error handler

Author: trowski

src/Loop.php

@@ -388,12 +388,12 @@ public static function getState($key)
      * @param callable(\Throwable|\Exception $error)|null $callback The callback to execute. `null` will clear the
      *     current handler.
      *
-     * @return void
+     * @return callable(\Throwable|\Exception $error)|null The previous handler, `null` if there was none.
      */
     public static function setErrorHandler(callable $callback = null)
     {
         $driver = self::$driver ?: self::get();
-        $driver->setErrorHandler($callback);
+        return $driver->setErrorHandler($callback);
     }
 
     /**

src/Loop/Driver.php

@@ -246,7 +246,7 @@ final public function getState($key)
      * @param callable(\Throwable|\Exception $error)|null $callback The callback to execute. `null` will clear the
      *     current handler.
      *
-     * @return void
+     * @return callable(\Throwable|\Exception $error)|null The previous handler, `null` if there was none.
      */
     abstract public function setErrorHandler(callable $callback = null);