src/vs/platform/files/common/fileService.ts/FileService/doValidateCreateFile
class FileService:	private async doValidateCreateFile(resource: URI, options?: ICreateFileOptions): Promise<void> {

		// validate overwrite
		if (!options?.overwrite && await this.exists(resource)) {
			throw new FileOperationError(localize('fileExists', "Unable to create file '{0}' that already exists when overwrite flag is not set", this.resourceForError(resource)), FileOperationResult.FILE_MODIFIED_SINCE, options);
		}
	}