strict null checks in TypeScript

[Veetaha]

While studying your source code to finish with rust-lang/rust-analyzer#3053 I've stumbled with these lines of code.

vscode-cpptools/Extension/src/githubAPI.ts

Lines 38 to 43 in 3fa056f

	const downloadUrl: string = build.assets.find(asset => {
	return asset.name === vsixName;
	}).browser_download_url;
	if (!downloadUrl) {
	throw new Error(`Failed to find VSIX: ${vsixName} in build: ${build.name}`);
	}

From my perspective, it is apparent that if the release doesn't contain the needed .vsix file (which is a developer mistake that should never happen) you will get TypeError: Cannot read property 'browser_download_url' of undefined, instead of undefined written to downloadUrl. Thus, that true branch of the if statement is unreachable now.

Proof

In order to avoid such mistakes I strongly recommend you to set "strictNullChecks": true in tsconfig.json. The migration process for it is pretty straightforward, you just slap non-null assertions (i.e. postfix ! operator) everywhere the compiler sees a bug and later fix these places.

[Colengms]

Hi @Veetaha . Thanks for the bug report and the suggestion to enable strictNullChecks. We will take a look.

[sean-mcmanus]

@Colengms FYI, I looked into the structNullChecks several months ago, and it required a lot of changes. VS Code switched to using that last year.

Also, don't make these changes until I get my newMultiRoot2 branch checked in.

[Veetaha]

One cannot underestimate the power of strictNullChecks. This is an elegant solution to so-called 1-billion-dollar mistake.

In order to switch to strict-null-checks you can give me up to an hour or two and I will put postfix ! operators everywhere where the nullability is unsound according to TypeScript compiler. This way you just silence the errors and get strict-null checks from day 1. This means that new code will already use them. After that it is just a matter of time and incremental updates to figure out which types are indeed nullable and which are not to add null | T types and remove all unsound postfix ! operators (i.e. non-null assertions)