Fix noFallthroughCasesInSwitch/jsx object is not extensible

[ryota-murakami]

Relative Issues #9868#9429

I fixed broken yarn start that cause react-scripts can't handle correctly noFallthroughCasesInSwitch and jsx compileOptions.

Thank you for your decent review 😀

[mrmckeb]

@iansu@ianschmitz I've had this reported to me privately too, this seems like a change to the behaviour of ts.readConfigFile where the object is no longer extensible.

[mrmckeb]

Re-running CI.

[benneq]

@ryota-murakami Have you check the inner properties of compilerOptions? Those should be frozen, too. Though a simple appTsConfig.compilerOptions = { ...appTsConfig.compilerOptions }; might not work.

[ryota-murakami]

@benneq@KonstantinSimeonov I'm sorry for slow response.

Have you check the inner properties of compilerOptions? Those should be frozen, too. Though a simple appTsConfig.compilerOptions = { ...appTsConfig.compilerOptions }; might not work.

I've checked inner properties of compilerOptions are frozen.
Bellow screenshot showing Object.isFrozen(appTsConfig.compilerOptions.module) return true after destructured property of appTsConfig.compilerOptions on new Object.

And I'll share video clip that recorded running bellow code without Error.

if(appTsConfig.compilerOptions==null){appTsConfig.compilerOptions={};firstTimeSetup=true;}else{appTsConfig.compilerOptions={ ...appTsConfig.compilerOptions};for(constoptioninappTsConfig.compilerOptions){if(!Object.isFrozen(option))newError('appTsConfig.compilerOptions option should be frozen')}}

https://www.dropbox.com/s/912pp3xudr9rn9s/Screen%20Recording%202020-10-30%20at%2021.40.54.mov?dl=0

[KonstantinSimeonov]

@ryota-murakami

for(constoptioninappTsConfig.compilerOptions){if(!Object.isFrozen(option))newError('appTsConfig.compilerOptions option should be frozen')}

This is iterating over the keys of the object, which are strings and are always frozen and is not checking whether the properties are frozen or not 😛 . I think @benneq 's idea was to make sure that no crashes would occur if any of appTsConfig.compilerOptions's properties is frozen. Although I think that this is unlikely, you can safeguard against it by deep cloning the whole object.

[ryota-murakami]

@KonstantinSimeonov Thanks, that iterator is garbage 😅
And merge your suggested solution. I confirm that working.

But I don't understand why guys care about property frozen status?
This problem root is Object isn't extensible, co script couldn't add suggested config.
I think it doesn't matter frozen status 🤔

[ianschmitz]

Thanks folks!

[ryota-murakami]

@benneq@KonstantinSimeonov I got it why should we handle isFroze() result of each compileOptions.
If isFroze(someOption) === true and original config from reading files value is different from CRA suggested,
the script couldn't apply change to suggested value.

Thank you for your support about this PR!

[vegawong]

@ianschmitz should it make a new release version?

[cseas]

Can we please have a release with this fix? The problem is occurring for a lot of people in #9868