[completion] Don't suggest duplicates when uniqueItems: true

[zardoy]

However, I'm still thinking of clean way to handle boolean and null completions. I wonder why for these types information is written into types argument, instead of collector as completion directly?

vscode-json-languageservice/src/services/jsonCompletion.ts

Line 667 in db2fd8f

private collectTypes(schema: JSONSchema, types: { [type: string]: boolean }) {

Edit: I see why it happens for object and array types, but I still don't understand why don't add completions for boolean and null directly in that function.

[aeschli]

Thanks @zardoy !