Update EmbeddedContentButton.php

Closes #3491478

src/Entity/EmbeddedContentButton.php

@@ -104,7 +104,7 @@ final class EmbeddedContentButton extends ConfigEntityBase implements EmbeddedCo
     foreach ($patterns as $pattern) {
       // Allow for regex patterns.
       try {
-        if ((bool) preg_match($pattern, $plugin_id)) {
+        if ((bool) @preg_match($pattern, $plugin_id)) {
           return TRUE;
         }
       }