When no page is passed, set page to be 0

Editor assessment

The subject states the rule, page defaults to zero when absent, and the body earns real credit by explaining the failure being prevented: the page parameter reached Mongoose as NaN and caused strange errors. That is a genuine why-and-symptom pair in one sentence, exactly what a small fix message should carry, and it lets a reader judge the change without the diff. No scope, a minor gap where api would fit; no footers needed. Hygiene is good: imperative, period-free, no junk. A compact, instructive fix message with only trivial flaws.