fix: Typo in a preprocessor directive This is a regression of commit 2519a03418af2108d3bd8c269ba01ab72ae240ef "refactor: Clean up the checking of chunk lengths and allocation limits" Compilation would break under the "right" non-default configuration. (Oopsie!) Also clean up comments in the surrounding code. Reported-by: chris0e3 <chris0e3@gmail.com> Signed-off-by: Cosmin Truta <ctruta@gmail.com>