script: remove dead code in CountWitnessSigOps #33786

1. 
   l0rinc commented at 9:53 pm on November 4, 2025: contributor

   Found while reviewing #32840

   The nullptr witness path was dead in normal code paths: replacing it with reference enables us deleting unreachable logic.

   Code coverage proof: https://maflcko.github.io/b-c-cov/total.coverage/src/script/interpreter.cpp.gcov.html#L2135

2. refactor: remove dead code in `CountWitnessSigOps`

   Found while reviewing #32840
   
   The `nullptr` witness path was dead in normal code paths: removing it deletes unreachable logic.
   
   Code coverage proof:
   https://maflcko.github.io/b-c-cov/total.coverage/src/script/interpreter.cpp.gcov.html#L2135

   24bcad3d4d
3. DrahtBot added the label Consensus on Nov 4, 2025
4. 
   DrahtBot commented at 9:53 pm on November 4, 2025: contributor

   The following sections might be updated with supplementary metadata relevant to reviewers and maintainers.

   Code Coverage & Benchmarks

   For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/33786.

   Reviews

   See the guideline for information on the review process.

   Type	Reviewers
   ACK	darosior, stickies-v, kevkevinpal, maflcko

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   Conflicts

   Reviewers, this pull request conflicts with the following ones:

   • #32317 (kernel: Separate UTXO set access from validation functions by TheCharlatan)

   If you consider this pull request important, please also help to review the conflicting pull requests. Ideally, start with the one that should be merged first.

5. darosior approved
6. 
   darosior commented at 11:26 pm on November 4, 2025: member

   Neat. utACK 24bcad3d4df59690f30c9df8ebb62f0bddd0f1c7.

   The need for a pointer was removed when CTxInWitness was moved into CTxIn in f6fb7acda4aefd01b8ef6cd77063bfc0c4f4ab36.

7. l0rinc marked this as ready for review on Nov 4, 2025
8. stickies-v approved
9. 
   stickies-v commented at 12:01 pm on November 5, 2025: contributor

   ACK 24bcad3d4df59690f30c9df8ebb62f0bddd0f1c7
10. 
    kevkevinpal commented at 8:10 pm on November 5, 2025: contributor

    ACK 24bcad3
11. 
    maflcko commented at 4:06 pm on November 6, 2025: member

    review ACK 24bcad3d4df59690f30c9df8ebb62f0bddd0f1c7 🐏

    Signature:

    0untrusted comment: signature from minisign secret key on empty file; verify via: minisign -Vm "${path_to_any_empty_file}" -P RWTRmVTMeKV5noAMqVlsMugDDCyyTSbA3Re5AkUrhvLVln0tSaFWglOw -x "${path_to_this_whole_four_line_signature_blob}"
    1RUTRmVTMeKV5npGrKx1nqXCw5zeVHdtdYURB/KlyA/LMFgpNCs+SkW9a8N95d+U4AP1RJMi+krxU1A3Yux4bpwZNLvVBKy0wLgM=
    2trusted comment: review ACK 24bcad3d4df59690f30c9df8ebb62f0bddd0f1c7 🐏
    3hj6nIxI+40vPxamIgbX5LlbpRouEUxYZY48TXPn9b4qzVEGLo6G5sBwEiRQKpq2+LSPlEhKOLRkvjKpFnlFqBA==
    

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l0rinc DrahtBot darosior stickies-v kevkevinpal maflcko

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