Replace 'del' dependency by built-in recursive fs.rm

[craigahobbs]

Node.js 14 supports recursive file deletion, which makes the del dependency unnecessary.

[novemberborn]

Thanks @craigahobbs. I don't think this materially impacts the dependency size (notice how package-lock.json wasn't changed) but we should use built-in methods when appropriate.

[novemberborn]

This isn't needed when force: true.

[craigahobbs]

@novemberborn, package-lock.json is a reflection of all dependencies including devDependencies, which is a much larger dependency list. Most end-users users only require the non-devDependencies.

To measure the change in total non-devDependencies, do an "npm install --omit dev" and check the total installed packages count. I used the top-level node_modules file count as a reasonable approximation:

$ rm -rf node_modules
$ npm install --omit dev
$ ls -1 node_modules | wc -l

Here's what I get before/after:

**before: ** 143
**after: ** 127

In other words, after the change, for non-development usage, 16 fewer packages are installed.

[novemberborn]

Here's what I get before/after:

**before: ** 143 **after: ** 127

In other words, after the change, for non-development usage, 16 fewer packages are installed.

You can't compare it that way. Fewer dependencies may be hoisted because they're no longer shared, but that doesn't mean they're not installed.

[craigahobbs]

Do you mean that, for any package that lists Ava as a development dependency, that just because we eliminate "del" from Ava's runtime dependencies that it might get installed by another of the package's development dependencies? And so on with sub-dependencies? If so, that's valid, but many packages will get some of the possible benefit (16).