Consider loose completions in the syntax server on unresolved/error types

Assume that no type named Foo exists in the current project, and assume the current file.

export let x: Foo;

x./**/

When requesting completions at /**/, we should consider giving a list of identifiers in the current file, similar to what we do for any in JavaScript files. This contrived example isn't great, but when opening a larger file, this could be helpful.

This is somewhat related to

• https://github.com/microsoft/TypeScript/issues/5334, where we considered giving identifier completions whenever hitting any
• https://github.com/microsoft/TypeScript/issues/39032, where we discussed producing these special loading types and unresolved error types.

Inizia tracciando la gestione del completamento di syntax-server per i tipi non risolti o di errore, quindi confrontala con i completamenti degli identificatori per any in JavaScript. Leggi le issue #5334 e #39032 per il contesto. Il lavoro è completato quando la posizione mostrata può proporre identificatori dal file corrente senza alterare il comportamento esistente del completamento.