Remove usage of assert.invariant

[eliandoran]

I was using php-serialize at client level using Svelte and Vite, when it warned me at build time:

[plugin:vite:resolve] Module "assert" has been externalized for browser compatibility, imported by "/home/elian/Projects/toolkit/node_modules/php-serialize/lib/esm/unserialize.js". See http://vitejs.dev/guide/troubleshooting.html#module-externalized-for-browser-compatibility for more details.

Apparently this is due to the fact that assert is a Node module, so it has to embed this module to work in the browser.

I've looked at the uses of invariant in the code base and they are only a few, so I thought about replacing them with simple guard statements instead.

[steelbrain]

Hello! Thanks for taking the time to contribute. Instead of inlining these checks, how do you feel about creating a helper function that broadly matches the signature of invariant and use that instead?

[eliandoran]

@steelbrain , sure, no problem with that.

I saw there were only a few of them, but maybe it's more elegant to have a helper function.

[eliandoran]

@steelbrain , done.

I've noticed that the tests pass even if I negate the if in invariant, so it might be worth checking if it's possible to improve the code coverage. Never mind, apparently I had to run npm run prepare before npm run test.

[steelbrain]

Thank you for working on this, minor nit and then we're good

[eliandoran]

Apparently the yarn lint command fails for some reason.

EDIT: It was the linter, apparently I did not notice that the project does not use semicolons.

[steelbrain]

Thanks again!

[steelbrain]

Published in https://github.com/steelbrain/php-serialize/releases/tag/v5.0.0