Fix crash on umd and module merge, allow umds to be accessed when merged with a non-UMD symbol

[weswigham]

Fixes #28762

[sheetalkamat]

Wasn't that error correct?

[weswigham]

Not really, no. If there's a global augmentation adding a thing to the global scope, then it should be globally accessible, period.

[sheetalkamat]

But aren't the globals accessible from module? They are only accessible from non module file?

[weswigham]

Today, the umd declaration poisons the symbol unconditionally (irrespective of other things the symbol may have merged with). With this change, the UMD declaration only errors on access if every declaration of the symbol is a UMD declaration.

[chrisbenti]

Works for me 😄

[weswigham]

@DanielRosenwasser since this fixes a crash, do we want to port it to 3.2?

[chrisbenti]

This is an active 3.2 blocker for a few of our repos so I'd very much appreciate it 😄

[xueyu2010]

+1 this is a blocker for my project as well, much appreciated if this fix can be released soon.
Is there any interim fix I can avoid this exception?

[weswigham]

Yesterday's nightly should've included the fix, so installing typescript@next should work for the interim.

[xueyu2010]

Yesterday's nightly should've included the fix, so installing typescript@next should work for the interim.

Thanks, works for me 😀