src/vs/workbench/api/common/extHostDiagnostics.ts/DiagnosticCollection/get
class DiagnosticCollection:	get(uri: URI): ReadonlyArray<vscode.Diagnostic> {
		this._checkDisposed();
		const result = this.#data.get(uri);
		if (Array.isArray(result)) {
			return Object.freeze(result.slice(0));
		}
		return [];
	}