[xdl] fix expo export --dump-sourcemap for sdk 40+ and bare projects

[esamelson]

Fixes expo/expo#11652

Currently, JS bundles created from expo export --dump-sourcemap do not run in an SDK 40 bare project -- they fail with the familiar Module AppRegistry is not a registered callable module error. The cause seems to be the following lines:

expo-cli/packages/xdl/src/Project.ts

Lines 495 to 496 in 62339b5

	await truncateLastNLines(iosJsPath, 1);
	await truncateLastNLines(androidJsPath, 1);

The line that's being truncated is:

eric@Erics-iMac SelfHostTest % cat bundles/android-bcbcf3a727c6c6465382b49ddcf806e8.js
...
__r(0);

The bundles run fine without this line truncated. Since I'm not sure of the context/reasoning around truncating this line in the first place, I've simply added a gate that doesn't truncate for SDK 40+ bare projects.

Test plan

• self-hosted update created with expo export --dump-sourcemap loads and runs
• also verified there is only one sourceMappingURL present in the bundle (the one added right below the relevant code in expo-cli):

eric@Erics-iMac SelfHostTest % cat dist/bundles/android-ed94ad221ad84051ddc6d46b5aef6ada.js | grep "sourceMappingURL"
//# sourceMappingURL=android-ed94ad221ad84051ddc6d46b5aef6ada.map

@quinlanj , adding you as a reviewer just in case you remember any context around this from 2 years ago 😅

[RodolfoGS]

I tested and now works. Thank you so much for the fix 🎉

[quinlanj]

i honestly dont remember why i was truncating the lines 😅 There could have been something there which we didn't want in the exported bundles, or it could have been for aesthetic reasons. i definitely should have left a comment in the code tho, sorry :(

[esamelson]

thanks for the feedback, all 🙏 discussing with @brentvatne , we decided to change the logic slightly so the critical line now reads:
if (target === 'managed' && semver.lt(exp.sdkVersion, '40.0.0'))
meaning that we will only truncate lines for managed SDK 39 and lower projects -- or in other words, we won't truncate for projects that are either bare, or managed SDK 40+. (Confirmed this is an issue for managed SDK 40 projects as well, currently.)