extensions/typescript-language-features/web/webServer.ts/MainProcessLogger/write
class MainProcessLogger:	protected override write(body: string, type: ts.server.Msg) {
		let level: MessageLogLevel;
		switch (type) {
			case ts.server.Msg.Info:
				level = 'info';
				break;
			case ts.server.Msg.Perf:
				level = 'perf';
				break;
			case ts.server.Msg.Err:
				level = 'error';
				break;
			default:
				assertNever(type);
		}
		this.host.writeMessage({
			type: 'log',
			level,
			body,
		} as LoggingMessage);
	}