The wavy-dot may encourage unnecessary chaining promise

[JLHwung]

If we would like to access deep properties of the resolved data

await p.then(t => t.a.b)

we could use (await p~.a).b. But it is ideal because if .b throws, the error will be thrown at a different frame.

However, users may find out, await p~.a~.b, which seems neater than (await p~.a).b, also work because it can desugar to

await p.then(t => t.a).then(s => s.b)

By this way the wavy-dot could encourage unnecessary chaining promise. The broader question, as I mentioned in tc39/proposal-eventual-send#18, is that the wavy dot, while provides convenience to chain promise, limits the syntax operation that you can perform on the retrieved data. In this case the data access have to be separated into another execution frame.