Issue #3306131: Passing null to parameter #1 ($path) of type string is deprecated on template_preprocess_image_style

core/modules/image/image.module

@@ -273,7 +273,7 @@ function template_preprocess_image_style(&$variables) {
   // If the current image toolkit supports this file type, prepare the URI for
   // the derivative image. If not, just use the original image resized to the
   // dimensions specified by the style.
-  if ($style->supportsUri($variables['uri'])) {
+  if (isset($variables['uri']) && $style->supportsUri($variables['uri'])) {
     $variables['image']['#uri'] = $style->buildUrl($variables['uri']);
   }
   else {