Index: SingleFieldContainer.php
@@ -138,7 +138,9 @@
         // JavaScript code for event handlers:
         $parameterArray['fieldChangeFunc'] = array();
         $parameterArray['fieldChangeFunc']['TBE_EDITOR_fieldChanged'] = 'TBE_EDITOR.fieldChanged(' . GeneralUtility::quoteJSvalue($table) . ',' . GeneralUtility::quoteJSvalue($row['uid']) . ',' . GeneralUtility::quoteJSvalue($fieldName) . ',' . GeneralUtility::quoteJSvalue($parameterArray['itemFormElName']) . ');';
-        $parameterArray['fieldChangeFunc']['alert'] = $alertMsgOnChange;
+        if (!empty($alertMsgOnChange)) {
+            $parameterArray['fieldChangeFunc']['alert'] = $alertMsgOnChange;
+        }
 
         // If this is the child of an inline type and it is the field creating the label
         if ($this->isInlineChildAndLabelField($table, $fieldName)) {