Issue #2194111 by sun: Error handler throws exception when service container...

Issue #2194111 by sun: Error handler throws exception when service container is not (fully) available yet.

core/includes/bootstrap.inc

@@ -1300,7 +1300,7 @@ function watchdog($type, $message, array $variables = NULL, $severity = WATCHDOG
 
   // It is possible that the error handling will itself trigger an error. In that case, we could
   // end up in an infinite loop. To avoid that, we implement a simple static semaphore.
-  if (!$in_error_state && function_exists('module_implements')) {
+  if (!$in_error_state && \Drupal::hasService('module_handler')) {
     $in_error_state = TRUE;
 
     // The user object may not exist in all conditions, so 0 is substituted if needed.

core/includes/errors.inc

@@ -169,7 +169,7 @@ function _drupal_log_error($error, $fatal = FALSE) {
     }
   }
 
-  if (\Drupal::request()->isXmlHttpRequest()) {
+  if (\Drupal::hasRequest() && \Drupal::request()->isXmlHttpRequest()) {
     if ($fatal) {
       if (error_displayable($error)) {
         // When called from JavaScript, simply output the error message.

core/lib/Drupal.php

@@ -149,6 +149,16 @@ public static function hasService($id) {
     return static::$container && static::$container->has($id);
   }
 
+  /**
+   * Indicates if there is a currently active request object.
+   *
+   * @return bool
+   *   TRUE if there is a currently active request object, FALSE otherwise.
+   */
+  public static function hasRequest() {
+    return static::$container && static::$container->has('request') && static::$container->initialized('request') && static::$container->isScopeActive('request');
+  }
+
   /**
    * Retrieves the currently active request object.
    *