fix(Set Node): Do not stringify null and undefined (#7313)

Github issue / Community forum post (link here to close automatically):
https://community.n8n.io/t/null-and-undefined-in-string-fields/31060/1

packages/nodes-base/nodes/Set/Set.node.ts

@@ -12,13 +12,14 @@ export class Set extends VersionedNodeType {
 			icon: 'fa:pen',
 			group: ['input'],
 			description: 'Add or edit fields on an input item and optionally remove other fields',
-			defaultVersion: 3,
+			defaultVersion: 3.1,
 		};
 
 		const nodeVersions: IVersionedNodeType['nodeVersions'] = {
 			1: new SetV1(baseDescription),
 			2: new SetV1(baseDescription),
 			3: new SetV2(baseDescription),
+			3.1: new SetV2(baseDescription),
 		};
 
 		super(nodeVersions, baseDescription);

packages/nodes-base/nodes/Set/v2/SetV2.node.ts

@@ -21,7 +21,7 @@ const versionDescription: INodeTypeDescription = {
 	name: 'set',
 	icon: 'fa:pen',
 	group: ['input'],
-	version: 3,
+	version: [3, 3.1],
 	description: 'Change the structure of your items',
 	subtitle: '={{$parameter["mode"]}}',
 	defaults: {

packages/nodes-base/nodes/Set/v2/helpers/utils.ts

@@ -159,13 +159,26 @@ export const validateEntry = (
 	node: INode,
 	itemIndex: number,
 	ignoreErrors = false,
+	nodeVersion?: number,
 ) => {
 	let entryValue = entry[entry.type];
 	const name = entry.name;
 	const entryType = entry.type.replace('Value', '') as FieldType;
 
+	const description = `To fix the error try to change the type for the field "${name}" or activate the option “Ignore Type Conversion Errors” to apply a less strict type validation`;
+
 	if (entryType === 'string') {
-		if (typeof entryValue === 'object') {
+		if (nodeVersion && nodeVersion > 3 && (entryValue === undefined || entryValue === null)) {
+			if (ignoreErrors) {
+				return { name, value: null };
+			} else {
+				throw new NodeOperationError(
+					node,
+					`'${name}' expects a ${entryType} but we got '${String(entryValue)}' [item ${itemIndex}]`,
+					{ description },
+				);
+			}
+		} else if (typeof entryValue === 'object') {
 			entryValue = JSON.stringify(entryValue);
 		} else {
 			entryValue = String(entryValue);
@@ -179,7 +192,6 @@ export const validateEntry = (
 			validationResult.newValue = entry[entry.type];
 		} else {
 			const message = `${validationResult.errorMessage} [item ${itemIndex}]`;
-			const description = `To fix the error try to change the type for the field "${name}" or activate the option “Ignore Type Conversion Errors” to apply a less strict type validation`;
 			throw new NodeOperationError(node, message, {
 				itemIndex,
 				description,

packages/nodes-base/nodes/Set/v2/manual.mode.ts

@@ -191,7 +191,13 @@ export async function execute(
 				);
 			}
 
-			const { name, value } = validateEntry(entry, node, i, options.ignoreConversionErrors);
+			const { name, value } = validateEntry(
+				entry,
+				node,
+				i,
+				options.ignoreConversionErrors,
+				node.typeVersion,
+			);
 			newData[name] = value;
 		}