Server exception not caught is lock file is not writable

lib/lock.js の25行目付近から始め、ロックファイルを作成できない場合の EACCES エラーを再現します。拒否された操作が GET ハンドラーに到達する経路を追跡し、このケースでサーバーが未処理の promise rejection を発生させなくなっていることを確認します。

Mon, 27 Jan 2020 22:26:29 GMT solid:get GET -- Error: undefined EACCES: permission denied, mkdir '/Library/WebServer/Documents/profile/card$.ttl.lock'
(node:1964) UnhandledPromiseRejectionWarning: TypeError: releaseLock is not a function
    at Promise (/devel/github.com/solid/node-solid-server/lib/lock.js:25:13)
    at <anonymous>
(node:1964) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 105274)
Mon, 27 Jan 2020 22:26:30 GMT solid:get GET -- Error: undefined EACCES: permission denied, mkdir '/Library/WebServer/Documents/timbl/Public/Archive/linkeddata/chat/2019/08/23/chat.ttl.lock'
(node:1964) UnhandledPromiseRejectionWarning: TypeError: releaseLock is not a function
    at Promise (/devel/github.com/solid/node-solid-server/lib/lock.js:25:13)
    at <anonymous>
(node:1964) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 105275)