fix(54463): Move to existing file — Error: Debug Failure. at doChange4

[a-tarasyuk]

Fixes #54463

This issue is a regression - If the source file doesn't exist in the program, the refactoring should generate a new file. However, there is a scenario where the file exists but is not included in the list of program files.

@DanielRosenwasser I'm not certain if it is acceptable to parse the existing file and add changes to it.

[andrewbranch]

We decided that cross-project moves won’t be supported for now. I think the refactor just shouldn’t be offered if the target file exists but isn’t in the program.

[a-tarasyuk]

@andrewbranch Is it necessary to provide a specific message for that particular case?

[andrewbranch]

I think that would be good, but we might need to discuss what the message should be. The problem is that inferred projects only contain open files, so this feature is very limited for users with no tsconfig. They probably think of their project as all files in the open directory, but from TSServer’s point of view, the “project” is only the open files. So saying something like “Cannot move to file outside the current project” won’t make much sense to those users.