Fix non_streaming_server.py crash with --decoding-method modified_beam_search

[slipstr34m]

python-api-examples/non_streaming_server.py defines the flag as --max-active-paths (line 434) and consumes args.max_active_paths (line 970), but check_args() asserts on args.num_active_paths, which this script never defines. Starting the server with --decoding-method modified_beam_search (or with --hotwords-file, which check_args gates behind it) has always crashed at startup:

File ".../non_streaming_server.py", line 493, in check_args
    assert args.num_active_paths > 0, args.num_active_paths
AttributeError: 'Namespace' object has no attribute 'num_active_paths'

The gap dates to b094868 (#259), which adapted streaming_server.py (where the flag is consistently --num-active-paths) but renamed the flag without updating check_args. This aligns check_args with the name the script already defines and consumes, keeping the CLI unchanged; the greedy_search path is untouched.

Tested with sherpa-onnx-zipformer-en-2023-04-01: on master the command above crashes as shown; with this change the same command loads the model and binds the port (server listening on 0.0.0.0:16125). A greedy_search control starts cleanly before and after. Hit this while running the server locally for transcription and switching the decoding method.

Summary by CodeRabbit

• Bug Fixes
  • Corrected validation for the modified beam search option so the configured maximum active paths value is checked properly before recognition starts.

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ℹ️ Recent review info

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Run ID: 08327e17-1d6b-41e0-8e22-0755f0fb3af9

📥 Commits

Reviewing files that changed from the base of the PR and between 4f97006 and 76c08f0.

📒 Files selected for processing (1)

• python-api-examples/non_streaming_server.py

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📝 Walkthrough

Walkthrough

Corrects modified_beam_search argument validation in the non-streaming Python server to check max_active_paths before recognizer creation.

Changes

Modified beam search validation

Layer / File(s)	Summary
Correct maximum active paths validation python-api-examples/non_streaming_server.py	Validation now requires args.max_active_paths > 0 instead of referencing args.num_active_paths.

Estimated code review effort: 1 (Trivial) | ~2 minutes

Suggested reviewers: kfrancis

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly matches the main fix: a startup crash in non_streaming_server.py when using modified_beam_search.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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