parsing of αx leads to broken XMIR

[yegor256]

Try to add a new file with this content to phi-typos directory:

{⟦ k ↦ ξ.αx.t ⟧}

Test must pass, but they fail.

[yegor256]

@maxonfjvipon please, check

[maxonfjvipon]

@yegor256 there's no way it can be converted to EO, that's why it's prohibited

[yegor256]

@maxonfjvipon but it must not produce a broken XMIR (doesn't validate against XSD). It should create XMIR that has <error>, but not an incorrectly formatted XML

[maxonfjvipon]

On hold until #3946 (comment)

[yegor256]

@maxonfjvipon I see a recursion in your last message :)

[maxonfjvipon]

@yegor256 fixed