Script editor shows error abruptly

[Torguen]

Godot version

v3.5.stable.official [991bb6ac7]

System information

w10 64

Issue description

It's simple, look at the gif. Not even the autocomplete appears to help me write the method name. When you put "if" immediately the editor already shows the error: "the symbol : is not found at the end of the line". It doesn't even allow me to autocomplete the "existe_archivo" method name!. Autocomplete does not allow me to autocomplete the "existe_archivo" method.

Steps to reproduce

See the gif

Minimal reproduction project

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