add fallbackimage style null check

Author: woldtwerk

woldtwerk_image.module

@@ -99,19 +99,22 @@ function woldtwerk_image_preprocess_responsive_image(&$variables) {
 
   $fallback_image_style = ImageStyle::load($responsive_image_style
     ->getFallbackImageStyle());
-  $fallback_image_uri = $fallback_image_style->buildUri($variables['uri']);
   $image = \Drupal::service('image.factory')->get($variables['uri']);
-  $image_type = $image->getMimeType();
 
-  /* Create Image Style File if it doesn't exist */
-  if (!file_exists($fallback_image_uri)) {
-    $fallback_image_style->createDerivative($image->getSource(), $fallback_image_uri);
-  }
+  if ($fallback_image_style) {
+    $fallback_image_uri = $fallback_image_style->buildUri($variables['uri']);
+    $image_type = $image->getMimeType();
+
+    /* Create Image Style File if it doesn't exist */
+    if (!file_exists($fallback_image_uri)) {
+      $fallback_image_style->createDerivative($image->getSource(), $fallback_image_uri);
+    }
 
-  /* Check if createDerivative worked */
-  if (file_exists($fallback_image_uri)) {
-    $image_file = file_get_contents($fallback_image_uri);
-    $base_64_image = base64_encode($image_file);
-    $variables['base_64_data'] = "data:$image_type;base64,$base_64_image";
+    /* Check if createDerivative worked */
+    if (file_exists($fallback_image_uri)) {
+      $image_file = file_get_contents($fallback_image_uri);
+      $base_64_image = base64_encode($image_file);
+      $variables['base_64_data'] = "data:$image_type;base64,$base_64_image";
+    }
   }
 }