[3.8] Refactor web error handling (#5270).

[asvetlov]

(cherry picked from commit e9fdf0a)

Co-authored-by: Andrew Svetlov [email protected]

[codecov]

Codecov Report

Merging #5295 (e9fdf0a) into 3.8 (8ce3013) will decrease coverage by 0.37%.
The diff coverage is 96.39%.

@@            Coverage Diff             @@
##              3.8    #5295      +/-   ##
==========================================
- Coverage   97.53%   97.16%   -0.38%     
==========================================
  Files          44       41       -3     
  Lines        8844     8739     -105     
  Branches     1424     1402      -22     
==========================================
- Hits         8626     8491     -135     
- Misses        102      129      +27     
- Partials      116      119       +3     

Flag	Coverage Δ
unit	97.04% <96.13%> (-0.33%)	⬇️

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

Impacted Files	Coverage Δ
aiohttp/web_request.py	95.70% <ø> (-1.86%)	⬇️
aiohttp/web_response.py	98.09% <ø> (-0.18%)	⬇️
aiohttp/web_routedef.py	98.13% <ø> (+0.03%)	⬆️
aiohttp/web_runner.py	97.76% <ø> (+0.13%)	⬆️
aiohttp/web_server.py	94.28% <ø> (-5.72%)	⬇️
aiohttp/web_urldispatcher.py	97.83% <ø> (+0.23%)	⬆️
aiohttp/worker.py	97.45% <ø> (+0.73%)	⬆️
aiohttp/locks.py	92.85% <66.66%> (ø)
aiohttp/resolver.py	93.18% <76.92%> (-1.98%)	⬇️
aiohttp/web_app.py	97.30% <90.24%> (-1.60%)	⬇️
... and 69 more

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[lgtm-com]

This pull request introduces 2 alerts when merging 84079a5 into 135cb16 - view on LGTM.com

new alerts:

• 1 for Unused local variable
• 1 for Missing call to __init__ during object initialization