Update examples

[Antonito]

This PR updates examples/:

• to defer a peerConnection.Close call
• if relevant, cancel the execution on an ICE Disconnected event
• Use MimeType constants

This should hopefully fix #839.

Also updates TestNonFatalRead with a timeout, as it failed after 11 minutes on my previous PR (there seems to be some kind of deadlock, which I didn't investigate further).

[codecov]

Codecov Report

Merging #1856 (af62aa8) into master (8a0df90) will decrease coverage by 0.07%.
The diff coverage is n/a.

❗ Current head af62aa8 differs from pull request most recent head 4d3ab28. Consider uploading reports for the commit 4d3ab28 to get more accurate results

@@            Coverage Diff             @@
##           master    #1856      +/-   ##
==========================================
- Coverage   75.65%   75.58%   -0.08%     
==========================================
  Files          84       84              
  Lines        6046     6049       +3     
==========================================
- Hits         4574     4572       -2     
- Misses       1085     1088       +3     
- Partials      387      389       +2     

Flag	Coverage Δ
go	77.27% <ø> (-0.08%)	⬇️
wasm	71.26% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
dtlstransport.go	63.88% <0.00%> (-1.86%)	⬇️
settingengine.go	60.60% <0.00%> (+0.60%)	⬆️

---

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 8a0df90...4d3ab28. Read the comment docs.

[Sean-Der]

🔥 this is fantastic @Antonito! Thank you for grabbing all these long standing issues

[Sean-Der]

@Antonito Sorry for the long wait time on the review!

Can you print the error if peerConnection.Close() fails, want to encourage good logging :)

Can you do OnPeerConnectionState and look for PeerConnectionStateFailed. That way users catch DTLS errors as well. The PeerConnection can come back from disconnected. If you want to add a comment around 'Use disconnected if you are interested in detecting faster timeout' I am in support!

Call out what causes failure, and mention ICE restart. Wait until PeerConnection has had no network activity for 30 seconds or another failure. It may be reconnected using an ICE Restart.

[Antonito]

@Sean-Der No worries, I've been busy too!

I originally wanted to work with PeerConnectionStateFailed, but wrongly decided to follow blindly what was on the issue #839 – this should look better now! :)