Expand description
Checked storage operations shared by the parsed and typed AST arenas.
Errors carry storage metadata only. A compiler phase adds its stage without reading a potentially invalid node or using that node’s source span.
IDs remain arena-local indices, not ownership tokens. These operations check
storage bounds and capacity; they do not validate a node’s child IDs or spans.
The maximum node count is u32::MAX, matching the legacy arena allocation
invariant and leaving u32::MAX itself outside the allocated ID range.