feat: Add runtime config support

[julien1619]

This PR adds a new configuration key: publicRuntimeConfigKey, it defaults to sentry when publicRuntimeConfig exists.

It fixes #202, and inspired by #203, thanks to @Ledarath

[codecov]

Codecov Report

Merging #254 (2cd8968) into master (4a57102) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #254   +/-   ##
=======================================
  Coverage   55.55%   55.55%           
=======================================
  Files           1        1           
  Lines          27       27           
  Branches        8        8           
=======================================
  Hits           15       15           
  Misses          9        9           
  Partials        3        3           

Impacted Files	Coverage Δ
lib/module.js	55.55% <100.00%> (ø)

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[rchl]

Missing:

• documentation
• similar change in plugin.lazy.js
• What about server-side? Even though on server-side options are "runtime", the user might want to use the runtime config for both server and client-side rather than having to specify them in both places.

[julien1619]

Thanks for the review, I'll do that tomorrow.

[julien1619]

@rchl I did all the requested changes.

• Add documentation
• Replace deepmerge and all Object.assign by lodash.merge
• Add Runtime Config to lazy mode and server-side
• Restore serialize instead of JSON.stringify

[julien1619]

I've tested it on my site and there is a bug in the config merge, I'll investigate tomorrow. For now I'll set the draft mode on this Pull Request.

[julien1619]

It works now. @rchl can you review it again? Thanks!

[julien1619]

@rchl Just did a rebase onto master. Is there something blocking this PR from being merged? Thanks!

[rchl]

Just lack of time but will try to handle soon

[julien1619]

@rchl We did all the changes requested. The publicRuntimeConfig can now be used to override config, clientConfig and serverConfig (Thanks to @Ledarath ) Can you review it? Thanks!

[rchl]

Would you be able to enable the option that allows maintainers to push to this branch? I could do some minor changes myself instead of the long way with comments and turnarounds.

[julien1619]

Done! I invited you directly, the option "Allow edits from maintainers" wasn't available.

[rchl]

OK, I've done some changes. You can have a look through the commits I've added and check if it looks good to you.

[julien1619]

LGTM 👍

[rchl]

Thanks!

[samturrell]

Sorry to jump in on this late. To confirm, the dsn still has to be provided at build time and will be baked into the built code? There's no way of providing this as a runtime config value?

[rchl]

A bit weird maybe but you can probably set any dsn in build-time settings and override it through runtime settings.