fix(koa): End span and record exception on a middleware exception

[oguzbilgener]

Fixes #279

Not sure why the lint task failed, I did run npm run lint:fix prior to comitting.

ESLint couldn't find the config "./node_modules/gts" to extend from. Please check that the name of the config is correct.

The config "./node_modules/gts" was referenced from the config file in "/home/runner/work/opentelemetry-js-contrib/opentelemetry-js-contrib/detectors/node/opentelemetry-resource-detector-github/.eslintrc.js".

Which problem is this PR solving?

This PR fixes the problem where .end() is never called on the span for a middleware layer when the middleware layer throws an exception / rejects a promise.

The master branch fails on the test case that I added.

Short description of the changes

• Always call span.end() for the span that's created for a middleware layer. Also record the exception in the span (as an event), then rethrow it so the application can handle it.

I considered using the safeExecuteInTheMiddle utility function, but it doesn't look like it works well with async functions.

[linux-foundation-easycla]

The committers are authorized under a signed CLA.

• ✅ Oğuz Bilgener (03c1076)

[codecov]

Codecov Report

Merging #281 (4a0d41f) into master (0fe7949) will increase coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #281      +/-   ##
==========================================
+ Coverage   95.39%   95.41%   +0.01%     
==========================================
  Files         115      115              
  Lines        6061     6087      +26     
  Branches      591      592       +1     
==========================================
+ Hits         5782     5808      +26     
  Misses        279      279              

Impacted Files	Coverage Δ
.../node/opentelemetry-koa-instrumentation/src/koa.ts	98.11% <0.00%> (+0.07%)	⬆️
...opentelemetry-koa-instrumentation/test/koa.test.ts	99.30% <0.00%> (+0.13%)	⬆️