ISTWCMS-5128: ensuring that getting plain text field does not have undefined variable error

src/Service/UwNodeFieldValue.php

@@ -261,6 +261,8 @@ class UwNodeFieldValue {
    */
   public function getPlainText(Node $node, string $field_name, bool $multiple = FALSE) {
 
+    $plain_text = '';
+
     // If there are no multiple plain text, just return value.
     // If there are multiple plain text, step through and
     // get the values.