fix(h2): TypeError: Cannot read properties of null (reading 'servername') in _resume when H2 stream completes

[hxinhan]

This relates to...

#4846

The fix adds null check for request to avoid the following crash

TypeError: Cannot read properties of null (reading 'servername')
    at _resume (/opt/sye/node_modules/undici/lib/dispatcher/client.js:610:79)
    at resume (/opt/sye/node_modules/undici/lib/dispatcher/client.js:561:3)
    at Client.<computed> (/opt/sye/node_modules/undici/lib/dispatcher/client.js:285:31)
    at ClientHttp2Stream.<anonymous> (/opt/sye/node_modules/undici/lib/dispatcher/client-h2.js:720:22)
    at Object.onceWrapper (node:events:638:28)
    at ClientHttp2Stream.emit (node:events:536:35)
    at endReadableNT (node:internal/streams/readable:1698:12)
    at processTicksAndRejections (node:internal/process/task_queues:82:21)

[mcollina]

lgtm

[mcollina]

Linting is failing, can you fix it?

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.13%. Comparing base (85cde5d) to head (e92595f).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4847      +/-   ##
==========================================
- Coverage   93.14%   93.13%   -0.01%     
==========================================
  Files         109      109              
  Lines       34239    34243       +4     
==========================================
+ Hits        31891    31893       +2     
- Misses       2348     2350       +2     

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[metcoder95]

lint seems failing

[hxinhan]

Attempted to fix linting issue

[mcollina]

still lgtm