chore(lambda-nodejs): improve spawnSync error message

[blimmer]

This PR improves the error message when a lambda-nodejs function fails to bundle.

I'm working on moving a client's repository from a "makeshift monorepo" to a real yarn/lerna driven monorepo. They make heavy use of NodejsFunction, so I'm moving them to the newer reference project architecture with a single lockfile at the root of the repository.

While working through this issue, I kept running into this error message:

> yarn cdk diff
Bundling asset SomeLambdaHandler/SomeSubLambda/Lambda/Code/Stage...
Usage Error: Couldn't find a script named "esbuild".

$ yarn run [--inspect] [--inspect-brk] <scriptName> ...
Failed to bundle asset SomeLambdaHandler/SomeSubLambda/Lambda/Code/Stage, bundle output is located at /Users/blimmer/code/client/project/packages/some-workspace/cdk.out/bundling-temp-2f3ffba54d828547eb851ebe672a601943e153ec31fdc5e45f8e80ed976da6d3-error: Error: bash exited with status 1
Subprocess exited with error 1

This was confusing to me because I have esbuild installed in both sub-packages that require it. The error message just tells me that bash failed to run, which isn't very helpful.

However, when I set an interactive breakpoint, I got a lot more information about the failure. By digging into these arguments

aws-cdk/packages/@aws-cdk/aws-lambda-nodejs/lib/util.ts

Lines 56 to 57 in 507769a

	export function exec(cmd: string, args: string[], options?: SpawnSyncOptions) {
	const proc = spawnSync(cmd, args, options);

I can actually see what's being run and which directory it's run in.

argument	contents	comments
cmd	bash	this doesn't really tell me anything about what's happening
args	[ -c, "yarn run esbuild --bundle \"/Users/blimmer/code/client/project/packages/some-workspace/lib/some-sub-lambda/lambda/index.ts\" --target=node14 --platform=node --outfile=\"/Users/blimmer/code/client/project/packages/some-workspace/cdk.out/bundling-temp-2f3ffba54d828547eb851ebe672a601943e153ec31fdc5e45f8e80ed976da6d3/index.js\" --external:aws-sdk" ]	the second argument of this array actually represents the command being run - this is way more useful than just bash
options	{ ...lotsOfOtherStuff, cwd: '/Users/blimmer/code/client/project' }	cwd was actually crucial for me to fix this problem. because I see this is running in the root of the monorepo, it shows that I need to install esbuild there, instead of in the workspaces.

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By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license

[gitpod-io]

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• CodeBuild project: AutoBuildProject89A8053A-LhjRyN9kxr8o
• Commit ID: c61c3ee
• Result: SUCCEEDED
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Thank you for contributing! Your pull request will be updated from master and then merged automatically (do not update manually, and be sure to allow changes to be pushed to your fork).