[Python] Added none check while accessing active_process_bundle

[riteshghorse]

Fixes #23946

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[riteshghorse]

R: @tvalentyn

[github-actions]

Stopping reviewer notifications for this pull request: review requested by someone other than the bot, ceding control

[codecov]

Codecov Report

Merging #23947 (f68f24e) into master (d407b60) will decrease coverage by 0.00%.
The diff coverage is 50.00%.

@@            Coverage Diff             @@
##           master   #23947      +/-   ##
==========================================
- Coverage   73.52%   73.52%   -0.01%     
==========================================
  Files         707      707              
  Lines       95832    95832              
==========================================
- Hits        70463    70460       -3     
- Misses      24052    24055       +3     
  Partials     1317     1317              

Flag	Coverage Δ
python	83.32% <100.00%> (-0.01%)	⬇️

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

Impacted Files	Coverage Δ
...s/go/pkg/beam/core/runtime/graphx/schema/schema.go	66.00% <0.00%> (ø)
sdks/go/pkg/beam/register/iter.go	67.21% <50.00%> (ø)
sdks/go/pkg/beam/register/emitter.go	47.69% <100.00%> (ø)
...python/apache_beam/runners/worker/worker_status.py	76.66% <100.00%> (ø)
sdks/python/apache_beam/io/source_test_utils.py	88.47% <0.00%> (-1.39%)	⬇️
sdks/python/apache_beam/transforms/combiners.py	93.05% <0.00%> (-0.39%)	⬇️
...hon/apache_beam/runners/worker/bundle_processor.py	93.42% <0.00%> (-0.13%)	⬇️
...dks/python/apache_beam/options/pipeline_options.py	94.90% <0.00%> (+0.44%)	⬆️
... and 2 more

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