src/vs/platform/files/common/fileService.ts/FileService/withWriteProvider
class FileService:	private async withWriteProvider(resource: URI): Promise<IFileSystemProviderWithFileReadWriteCapability | IFileSystemProviderWithOpenReadWriteCloseCapability> {
		const provider = await this.withProvider(resource);

		if (hasOpenReadWriteCloseCapability(provider) || hasReadWriteCapability(provider)) {
			return provider;
		}

		throw new Error(`Filesystem provider for scheme '${resource.scheme}' neither has FileReadWrite nor FileOpenReadWriteClose capability which is needed for the write operation.`);
	}