src/vs/platform/files/common/fileService.ts/FileService/throwIfFileSystemIsReadonly
class FileService:	protected throwIfFileSystemIsReadonly<T extends IFileSystemProvider>(provider: T, resource: URI): T {
		if (provider.capabilities & FileSystemProviderCapabilities.Readonly) {
			throw new FileOperationError(localize('err.readonly', "Unable to modify readonly file '{0}'", this.resourceForError(resource)), FileOperationResult.FILE_PERMISSION_DENIED);
		}

		return provider;
	}