From 1a91fc2b67a6fb3382950f8a14dce8d48ba8d736 Mon Sep 17 00:00:00 2001
From: Jonathan Goldwasser <jonathan@goldwasserexchange.be>
Date: Wed, 18 Nov 2020 10:27:02 +0100
Subject: [PATCH] README and Error

---
 packages/@aws-cdk/aws-lambda-nodejs/README.md | 19 ++++++++++---------
 .../aws-lambda-nodejs/lib/function.ts         |  2 +-
 2 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/packages/@aws-cdk/aws-lambda-nodejs/README.md b/packages/@aws-cdk/aws-lambda-nodejs/README.md
index c57f78e687a56..2797329f7de35 100644
--- a/packages/@aws-cdk/aws-lambda-nodejs/README.md
+++ b/packages/@aws-cdk/aws-lambda-nodejs/README.md
@@ -79,14 +79,15 @@ Use the [default image provided by `@aws-cdk/aws-lambda-nodejs`](https://github.
 as a source of inspiration.
 
 ### Lock file
-The `NodejsFunction` tries to automatically determine your project lock file
-(`package-lock.json` or `yarn.lock`). When bundling in a Docker container, the
-path containing this lock file is used as the source (`/asset-input`) for the
-volume mounted in the container.
+The `NodejsFunction` requires a dependencies lock file (`yarn.lock` or
+`package-lock.json`). When bundling in a Docker container, the path containing this
+lock file is used as the source (`/asset-input`) for the volume mounted in the
+container.
 
-Alternatively, you can specify the `depsLockFilePath` prop manually. In this case you
-need to ensure that this path includes `entry` and any module/dependencies used
-by your function. Otherwise bundling will fail.
+By default, it will try to automatically determine your project lock file.
+Alternatively, you can specify the `depsLockFilePath` prop manually. In this
+case you need to ensure that this path includes `entry` and any module/dependencies
+used by your function. Otherwise bundling will fail.
 
 ### Configuring esbuild
 The `NodejsFunction` construct exposes some [esbuild](https://esbuild.github.io/) options via properties: `minify`, `sourceMaps` and `target`.
@@ -119,8 +120,8 @@ new lambda.NodejsFunction(this, 'my-handler', {
 ```
 
 The modules listed in `nodeModules` must be present in the `package.json`'s dependencies. The
-same version will be used for installation. If a lock file is detected (`package-lock.json` or
-`yarn.lock`) it will be used along with the right installer (`npm` or `yarn`).
+same version will be used for installation. The lock file (`yarn.lock` or `package-lock.json`)
+will be used along with the right installer (`yarn` or `npm`).
 
 ### Local bundling
 If esbuild is available it will be used to bundle your code in your environment. Otherwise,
diff --git a/packages/@aws-cdk/aws-lambda-nodejs/lib/function.ts b/packages/@aws-cdk/aws-lambda-nodejs/lib/function.ts
index 9f10ca8628b40..4145757cfcfb4 100644
--- a/packages/@aws-cdk/aws-lambda-nodejs/lib/function.ts
+++ b/packages/@aws-cdk/aws-lambda-nodejs/lib/function.ts
@@ -83,7 +83,7 @@ export class NodejsFunction extends lambda.Function {
     } else {
       const lockFile = findUp(LockFile.YARN) ?? findUp(LockFile.NPM);
       if (!lockFile) {
-        throw new Error('Cannot find a lock file. Please specify it with `depsFileLockPath`.');
+        throw new Error('Cannot find a package lock file (`yarn.lock` or `package-lock.json`). Please specify it with `depsFileLockPath`.');
       }
       depsLockFilePath = lockFile;
     }