TypeError: String.prototype.concat called on null or undefined (v0.6.1)

[sumanbh]

Describe the issue

Seeing the following error on v0.6.1. Code was previously working on v0.6.0 and earlier versions

TypeError: String.prototype.concat called on null or undefined
    at concat (<anonymous>)
    at transformFile.next (<anonymous>)
    at run.next (<anonymous>)
    at transform.next (<anonymous>)

I was able to narrow it down to this new null check added in v0.6.1:

https://github.com/facebook/stylex/blob/c48bea12d3f4109a0b6bcce7c68c807972c16620/packages/babel-plugin/src/utils/evaluate-path.js#L693

In our case, we hit the following condition first (isStringLiteral is true) https://github.com/facebook/stylex/blob/c48bea12d3f4109a0b6bcce7c68c807972c16620/packages/babel-plugin/src/utils/evaluate-path.js#L683-L691

^ which defines func as the string concat function but context remains undefined.

As a result, calling func later results in TypeError: String.prototype.concat called on null or undefined being thrown because context is undefined. https://github.com/facebook/stylex/blob/c48bea12d3f4109a0b6bcce7c68c807972c16620/packages/babel-plugin/src/utils/evaluate-path.js#L725

I was able to workaround this by setting context to val. Reverting the null check also works but unsure which is the correct solution.

Expected behavior

No errors when compiling valid code.

Steps to reproduce

See issue description.

Test case

No response

Additional comments

No response