feat: More hints to nodes (#10565)

Co-authored-by: Giulio Andreini <g.andreini@gmail.com>
Co-authored-by: Shireen Missi <94372015+ShireenMissi@users.noreply.github.com>

packages/nodes-base/nodes/Transform/Aggregate/Aggregate.node.ts

@@ -1,6 +1,7 @@
 import get from 'lodash/get';
 import isEmpty from 'lodash/isEmpty';
 import set from 'lodash/set';
+
 import {
 	NodeOperationError,
 	type IDataObject,
@@ -10,6 +11,8 @@ import {
 	type INodeTypeDescription,
 	type IPairedItemData,
 	NodeConnectionType,
+	type NodeExecutionHint,
+	NodeExecutionOutput,
 } from 'n8n-workflow';
 import { prepareFieldsArray } from '../utils/utils';
 import { addBinariesToItem } from './utils';
@@ -239,6 +242,7 @@ export class Aggregate implements INodeType {
 	async execute(this: IExecuteFunctions): Promise<INodeExecutionData[][]> {
 		let returnData: INodeExecutionData = { json: {}, pairedItem: [] };
 		const items = this.getInputData();
+		const notFoundedFields: { [key: string]: boolean[] } = {};
 
 		const aggregate = this.getNodeParameter('aggregate', 0, '') as string;
 
@@ -299,8 +303,13 @@ export class Aggregate implements INodeType {
 				if (fieldToAggregate !== '') {
 					values[_outputFieldName] = [];
 					for (let i = 0; i < items.length; i++) {
+						if (notFoundedFields[fieldToAggregate] === undefined) {
+							notFoundedFields[fieldToAggregate] = [];
+						}
+
 						if (!disableDotNotation) {
 							let value = get(items[i].json, fieldToAggregate);
+							notFoundedFields[fieldToAggregate].push(value === undefined ? false : true);
 
 							if (!keepMissing) {
 								if (Array.isArray(value)) {
@@ -317,6 +326,7 @@ export class Aggregate implements INodeType {
 							}
 						} else {
 							let value = items[i].json[fieldToAggregate];
+							notFoundedFields[fieldToAggregate].push(value === undefined ? false : true);
 
 							if (!keepMissing) {
 								if (Array.isArray(value)) {
@@ -410,6 +420,21 @@ export class Aggregate implements INodeType {
 			addBinariesToItem(returnData, aggregatedItems, keepOnlyUnique);
 		}
 
+		if (Object.keys(notFoundedFields).length) {
+			const hints: NodeExecutionHint[] = [];
+
+			for (const [field, values] of Object.entries(notFoundedFields)) {
+				if (values.every((value) => !value)) {
+					hints.push({
+						message: `The field '${field}' wasn't found in any input item`,
+						location: 'outputPane',
+					});
+				}
+			}
+
+			if (hints.length) return new NodeExecutionOutput([[returnData]], hints);
+		}
+
 		return [[returnData]];
 	}
 }