requirejs broken by corejs upgrade

[jods4]

This line of code inside createLoader() is now an issue for us, since the last corejs update (2.0.2):

bootstrapper/src/index.js

Line 47 in b6f1849

if (window.System) {

The whole story is a bit complicated and I'm not 100% sure what the fix should be...

We use requirejs as our AMD loader. This means that we shouldn't have window.System defined.

What triggered the issue is that corejs now contains a polyfill for System.global.
But by creating the System object, it fooled Aurelia into thinking that I have a System loader, which I don't. So the code crashes on the next line with System.normalizeSync is undefined.

Now, you might think "well, let's be more specific and test if (System && System.normalizeSync)". I think this would fix the short-term crash but I'm not sure if it's a long-term solution.

Consider this: in the future, what will happen when users finally upgrade to a modern browser that includes a built-in System loader?

Answer: Aurelia will think that I'm using the System loader... and nothing will work because I deploy optimized requirejs bundles.

I think it would be best if either:

• Aurelia tests for the presence of requirejs first: if (window.require) else if (window.System). Since there is no reason requirejs would be loaded unless I'm intending to use it; or
• Aurelia takes some explicit config at startup that says which loader I am using, no guessing game.

❗ This is a critical issue: without dirty work-arounds using Aurelia + latest corejs + requirejs simply does not work.

[EisenbergEffect]

Good news is that I was planning to make some improvements in there this week. So, I can address this then too.