[ck] Proper promise treatment to avoid UnhandledPromises

[mcortesi]

Description

When a sendTransaction is reject, we need to make sure every rejects promise is handled.

Usually, a user would do:

const res = await kit.sendTransaction(...)

await res.getHash()
await res.waitReceipt()

Others, may directly call res.waitReceipt() and don't call res.getHash().

The problem is when sendTransaction() fails, and thus both promises (hash & receipt) are rejected. The promises are created when the txResult is created, not when the methods are called. So we need to make sure we catch those errors.

This PR address that, by adding catch logic in both methods.

Tested

Manually, when factoring e2e transfer tests

[codecov]

Codecov Report

Merging #1219 into master will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff           @@
##           master   #1219   +/-   ##
======================================
  Coverage    66.1%   66.1%           
======================================
  Files         261     261           
  Lines        7618    7618           
  Branches      508     508           
======================================
  Hits         5036    5036           
  Misses       2485    2485           
  Partials       97      97

Flag	Coverage Δ
#mobile	66.1% <ø> (ø)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update b70e840...0f71b65. Read the comment docs.