[BryanFRD]

Summary

• Change TreeNode::insert_blob to return Result<()> instead of panicking on path conflicts
• Use anyhow::bail!() with a descriptive error message including the conflicting path
• Update all call sites (BulkRepoBuilder::set_file, append_dummy) to propagate errors
• Update tests to use unwrap() on insert_blob calls and test error case with unwrap_err()

Closes #54

[Copilot]

Pull request overview

This PR replaces a panic!() in the tree-building logic with structured error propagation so path conflicts surface as actionable Result errors instead of crashing the generator.

Changes:

• Changed TreeNode::insert_blob to return Result<()> and use anyhow::bail!() on path conflicts
• Updated BulkRepoBuilder::{set_file,append_dummy} to propagate insert_blob errors
• Updated unit tests to reflect the new fallible API and added an error-case assertion

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[Copilot]

insert_blob still allows a tree/blob conflict in the opposite direction: if a directory already exists at path (i.e., entries contains TreeEntry::Tree for that key) and you later call insert_blob("a", ...) after inserting something under a/, the else branch will silently replace the tree with a blob and effectively discard the subtree. Consider detecting TreeEntry::Tree(_) here and returning a conflict error instead of overwriting.

Suggested change

	self.entries
	.insert(path.to_string(), TreeEntry::Blob(blob_oid));
	match self.entries.get(path) {
	Some(TreeEntry::Tree(_)) => {
	bail!("path conflict: '{path}' is a tree, not a blob")
	}
	Some(TreeEntry::Blob(_)) | None => {
	self.entries
	.insert(path.to_string(), TreeEntry::Blob(blob_oid));
	}
	}

[Copilot]

The conflict error message can lose the full path once recursion descends (e.g., a conflict under a/b/... will report inserting b/... because path is the per-node relative path). If this error is intended for end users, consider threading the original full path (or an accumulated prefix) through recursion so the message consistently includes the full conflicting path.

[Copilot]

self.invalidate() runs before any conflict checks. On a conflict this leaves the tree logically unchanged but clears cached_oid, causing unnecessary recomputation if the caller recovers and continues. Consider invalidating only after a successful insertion (or only on the branch where a mutation actually happens).

[Copilot]

The new test only asserts the error contains the generic substring "path conflict". Since the PR goal is a descriptive message including the conflicting path, consider asserting that the error string also contains the conflicting segment (e.g. "f") and/or the attempted path (e.g. "f/g.txt") so regressions in the message content are caught.

Suggested change

	assert!(err.to_string().contains("path conflict"));
	let err_str = err.to_string();
	assert!(err_str.contains("path conflict"));
	assert!(err_str.contains("f"));
	assert!(err_str.contains("f/g.txt"));