fix(core): Prevent backend from loading duplicate copies of nodes packages

packages/cli/src/load-nodes-and-credentials.ts

@@ -18,6 +18,7 @@ import type {
 } from 'n8n-workflow';
 import { NodeHelpers, ApplicationError, ErrorReporterProxy as ErrorReporter } from 'n8n-workflow';
 import path from 'path';
+import picocolors from 'picocolors';
 import { Container, Service } from 'typedi';
 
 import {
@@ -146,6 +147,7 @@ export class LoadNodesAndCredentials {
 					path.join(nodeModulesDir, packagePath),
 				);
 			} catch (error) {
+				this.logger.error((error as Error).message);
 				ErrorReporter.error(error);
 			}
 		}
@@ -258,6 +260,13 @@ export class LoadNodesAndCredentials {
 		dir: string,
 	) {
 		const loader = new constructor(dir, this.excludeNodes, this.includeNodes);
+		if (loader.packageName in this.loaders) {
+			throw new ApplicationError(
+				picocolors.red(
+					`nodes package ${loader.packageName} is already loaded.\n Please delete this second copy at path ${dir}`,
+				),
+			);
+		}
 		await loader.loadAll();
 		this.loaders[loader.packageName] = loader;
 		return loader;

packages/core/src/DirectoryLoader.ts

@@ -1,5 +1,6 @@
 import glob from 'fast-glob';
-import { readFile } from 'fs/promises';
+import { readFileSync } from 'node:fs';
+import { readFile } from 'node:fs/promises';
 import type {
 	CodexData,
 	DocumentationLink,
@@ -350,18 +351,11 @@ export class CustomDirectoryLoader extends DirectoryLoader {
  * e.g. /nodes-base or community packages.
  */
 export class PackageDirectoryLoader extends DirectoryLoader {
-	packageName = '';
+	packageJson: n8n.PackageJson = this.readJSONSync('package.json');
 
-	packageJson!: n8n.PackageJson;
-
-	async readPackageJson() {
-		this.packageJson = await this.readJSON('package.json');
-		this.packageName = this.packageJson.name;
-	}
+	packageName = this.packageJson.name;
 
 	override async loadAll() {
-		await this.readPackageJson();
-
 		const { n8n } = this.packageJson;
 		if (!n8n) return;
 
@@ -391,6 +385,17 @@ export class PackageDirectoryLoader extends DirectoryLoader {
 		});
 	}
 
+	protected readJSONSync<T>(file: string): T {
+		const filePath = this.resolvePath(file);
+		const fileString = readFileSync(filePath, 'utf8');
+
+		try {
+			return jsonParse<T>(fileString);
+		} catch (error) {
+			throw new ApplicationError('Failed to parse JSON', { extra: { filePath } });
+		}
+	}
+
 	protected async readJSON<T>(file: string): Promise<T> {
 		const filePath = this.resolvePath(file);
 		const fileString = await readFile(filePath, 'utf8');
@@ -408,8 +413,6 @@ export class PackageDirectoryLoader extends DirectoryLoader {
  */
 export class LazyPackageDirectoryLoader extends PackageDirectoryLoader {
 	override async loadAll() {
-		await this.readPackageJson();
-
 		try {
 			const knownNodes: typeof this.known.nodes = await this.readJSON('dist/known/nodes.json');
 			for (const nodeName in knownNodes) {