Promise rejection is handled differently than in the browser

[tian000]

Describe the bug
In the browser, promise rejection in the callback causes the request method to reject. In node (this library), it results in an uncaught exception.

To Reproduce
Run this in the browser
await navigator.locks.request("test-key", async () => {throw new Error("stuff")}).catch(err => console.log("PROMISE REJECTED", err));

Run this in node
await locks.request("test-key", async () => {throw new Error("stuff")}).catch(err => console.log("PROMISE REJECTED", err));

Notice that we get a console log in the browser, but not in node.

Expected behavior
We should match the browser implementation.

[tshemsedinov]

Thanks! Fixed here: #55