fix: Dont crash when client is bound inside of push_scope

[untitaker]

See #159

[codecov-io]

Codecov Report

Merging #163 into master will decrease coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #163      +/-   ##
==========================================
- Coverage   67.53%   67.53%   -0.01%     
==========================================
  Files          28       28              
  Lines        2760     2766       +6     
  Branches      432      433       +1     
==========================================
+ Hits         1864     1868       +4     
- Misses        727      729       +2     
  Partials      169      169

Impacted Files	Coverage Δ
sentry_sdk/hub.py	77.5% <100%> (-0.34%)	⬇️

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