fix(n8n Form Trigger Node): Error if Respond to Webhook and respond node not in workflow

packages/nodes-base/nodes/Form/utils.ts

@@ -1,4 +1,9 @@
-import { jsonParse, type IDataObject, type IWebhookFunctions } from 'n8n-workflow';
+import {
+	NodeOperationError,
+	jsonParse,
+	type IDataObject,
+	type IWebhookFunctions,
+} from 'n8n-workflow';
 import type { FormField, FormTriggerData, FormTriggerInput } from './interfaces';
 
 export const prepareFormData = (
@@ -77,11 +82,44 @@ export const prepareFormData = (
 	return formData;
 };
 
+const checkResponseModeConfiguration = (context: IWebhookFunctions) => {
+	const responseMode = context.getNodeParameter('responseMode', 'onReceived') as string;
+	const connectedNodes = context.getChildNodes(context.getNode().name);
+
+	const isRespondToWebhookConnected = connectedNodes.some(
+		(node) => node.type === 'n8n-nodes-base.respondToWebhook',
+	);
+
+	if (!isRespondToWebhookConnected && responseMode === 'responseNode') {
+		throw new NodeOperationError(
+			context.getNode(),
+			new Error('No Respond to Webhook node found in the workflow'),
+			{
+				description:
+					'Insert a Respond to Webhook node to your workflow to respond to the form submission or choose another option for the “Respond When” parameter',
+			},
+		);
+	}
+
+	if (isRespondToWebhookConnected && responseMode !== 'responseNode') {
+		throw new NodeOperationError(
+			context.getNode(),
+			new Error(`${context.getNode().name} node not correctly configured`),
+			{
+				description:
+					'Set the “Respond When” parameter to “Using Respond to Webhook Node” or remove the Respond to Webhook node',
+			},
+		);
+	}
+};
+
 export async function formWebhook(context: IWebhookFunctions) {
 	const mode = context.getMode() === 'manual' ? 'test' : 'production';
 	const formFields = context.getNodeParameter('formFields.values', []) as FormField[];
 	const method = context.getRequestObject().method;
 
+	checkResponseModeConfiguration(context);
+
 	//Show the form on GET request
 	if (method === 'GET') {
 		const formTitle = context.getNodeParameter('formTitle', '') as string;