Function parse_raw_commit 

pub fn parse_raw_commit(bytes: &[u8]) -> Result<RawCommit, ReplayObjectError>

What: Parses a raw commit object from git cat-file commit output. Why: Replay reads the tree, encoding, and signature state, and keeps the rest as bytes.

In TS you’d write (pseudocode):

parseRawCommit(bytes); // throws TypeError without a tree header