Number(env.VECTOR_SIGNER_ACCOUNT_INDEX ?? '0') was never validated. Verified
against the real walletFromSeed: a NaN-producing value, a negative integer,
and a fractional value each derived a DIFFERENT, syntactically valid
addr1... wallet with no error anywhere in the chain, and describe() would
echo the nonsense value back as if nothing were wrong ("mnemonic (account
index NaN)"). Spend limits three lines away already fail loud on the same
shape of mistake (BigInt(...) throws on garbage) -- this applies that same
instinct here: parseAccountIndex() rejects anything that is not a
non-negative integer, naming the variable and the offending value.
Only called from the two MnemonicKeySource-constructing branches, not
unconditionally -- PrivateKeyKeySource never reads an account index, so a
leftover garbage VECTOR_SIGNER_ACCOUNT_INDEX must not block a
private-key-configured signer that never uses it. Pinned by its own test.
config.test.ts covers: NaN-producing input, a negative integer, a fractional
value, a valid value (cross-checked against a directly-constructed
MnemonicKeySource for the same wallet), the unset default, and the
PrivateKeyKeySource non-interference case. Verified by mutation (temporarily
disabling the guard) that exactly the three invalid-input tests fail and the
other three are unaffected -- see the task report.
Final whole-branch review, Fix 2 of 4.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
