fix: correct loop iteration syntax in MuSig2Sign

[Olexandr88]

Fix invalid loop iteration over slice length in MuSig2Sign

[gemini-code-assist]

Summary of Changes

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This pull request addresses a bug in the MuSig2Sign utility function where incorrect loop syntax was being used to iterate over private keys. By updating the range expressions, the code now correctly iterates over the slice elements, ensuring proper session handling during the nonce exchange process.

Highlights

• Loop Iteration Fix: Corrected the loop iteration syntax in the MuSig2Sign function by iterating directly over the slice instead of its length.

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[gemini-code-assist]

Code Review

This pull request refactors the range loops in utils/musig.go to use the more idiomatic range syntax for slices. Feedback identifies a logic error where the MuSig2Sign function fails when only one private key is provided because the signature combination loop is skipped, and also points out a typo in an error message.

[gemini-code-assist]

The MuSig2Sign function currently fails when len(privKeys) == 1. In this scenario, the signature combination loop (starting at line 66) is skipped, leaving the haveAllSigs variable as false. This subsequently triggers the error check at line 76, returning a "combining MuSig2 signatures failed" error. To make the function more robust, consider initializing haveAllSigs to len(privKeys) == 1 or handling the single-signer case explicitly. Additionally, note that there is a typo in the error message at line 77 ("combinging" should be "combining").

[starius]

This change is not needed. The code is already correct. See https://go.dev/doc/go1.22#language

[Olexandr88]

Thanks for the clarification! Closing the PR.