build(webpack): Use fork-ts webpack plugin

[billyvg]

This should decrease build times since we are only running either
babel-loader or ts-loader and not both. We should skip typechecking for
local dev (and instead run type checking in a forked process) and always
run type checking in CI.

This will also skip typechecking when building prod assets (which should
be fine since we run them in CI).

👀👀

[markstory]

Neat. 👏 for faster local builds.

[billyvg]

OK tested this with wrong types and CI fails properly.

[BYK]

Do we have numbers for the speed up?

[billyvg]

For TSX files (and incremental builds) I was seeing times from:

• before: 4-10 seconds
• after: 3-5 seconds for the initial build and an additional 3-5 seconds for type checking

[evanpurkhiser]

What needs to be done to getsentry for this?

[billyvg]

@evanpurkhiser Hmm what's the current state of ts in getsentry? We don't do type checking in there do we?

[evanpurkhiser]

No we don't, but building sentry happens in getsentry, thus having typescript configs over there, so we may potentially need to mirror things over there.

[billyvg]

We extend sentry config in getsentry though, so it should build sentry with sentry's webpack config, right?

[billyvg]

I've tested this and it rebuilds in sentry (edit: getsentry) using the fork plugin fine

[priscilawebdev]

@billyvg please fix conflicts :)

[evanpurkhiser]

I kind of dislike this style prop spreading, I think it's a tad hard to read) but 🤷‍♂

I'd maybe prefer to have variables for like, tsLoaderConfig and bableLoaderConfig and then down here have

...(!IS_CI ? [bableLoaderConfig] : [tsLoaderConfig]),

[billyvg]

hmmm the spread doesn't look like it's even necessary either

[evanpurkhiser]

This looks good to me

[jeffkwoh]

Not sure if needed, but might want to check if similar needs to be done for getsentry.
Otherwise LGTM

[billyvg]

Ugh Percy snapshots do not check out, holding off on mergin

[billyvg]

This is the emotion problem we are facing: emotion-js/emotion#1748 - The last time I updated the PR was before the emotion 10 change, so we did not see these percy diffs.

Edit: looks like it's just an issue with a ts configuration (preserve JSX).