Fix WS transport when the connection aborts

[lchenut]

Should fix waku-org/nwaku#2140

[codecov]

Codecov Report

Merging #967 (d804441) into unstable (60f9536) will increase coverage by 0.02%.
The diff coverage is 100.00%.

@@             Coverage Diff              @@
##           unstable     #967      +/-   ##
============================================
+ Coverage     83.20%   83.23%   +0.02%     
============================================
  Files            91       91              
  Lines         15308    15309       +1     
============================================
+ Hits          12737    12742       +5     
+ Misses         2571     2567       -4     

Files	Coverage Δ
libp2p/transports/wstransport.nim	86.04% <100.00%> (+0.06%)	⬆️

... and 3 files with indirect coverage changes

[Ivansete-status]

It looks reasonable to me, thanks!

Aside from that, this is the second time we have encountered an issue with an exception not being properly captured. The last time I remember it was related to the `TransportOsError' exception.

As a further enhancement, I suggest trying to capture more generic exceptions at the end of the block.
CC: @Menduist

[vpavlin]

I was not able to test it (could not find a simple way to get this exception thrown in nwaku:)), but it for sure makes sense to handle it.