Navigation title "Navigation" in .navigation.md is silently dropped

Environment

ERROR Cannot read properties of null (reading 'name')

Version

3.16.0

Reproduction

https://stackblitz.com/edit/github-xzzfd3yf

Description

I am writing the documentation for a gliding software with Nuxt Docus. One section covers the in-app navigation, so the menu item really needs to be called "Navigation". If I set exactly this title in the .navigation.md of that section, the menu item shows up without any label. Any other title, like "Navigation & Menu", works fine.

The cause is here: https://github.com/nuxt/content/blob/656a5ce1a8cb6af0b37dd577bf4e1522e03e3c11/src/runtime/internal/navigation.ts#L24-L25

A title that equals "navigation" (case insensitive) is replaced with an empty string, presumably to discard the auto generated title derived from the file name. This makes it impossible to explicitly use "Navigation" as a section title, and there is no warning that the title is being dropped.

Expected behavior

It should be possible to explicitly name a section "Navigation". Possible fixes:

• Only discard the title when it was not set explicitly in the frontmatter, instead of comparing the string value.
• Or set the title to undefined instead of an empty string, so the title from index.md or the generated directory title is used as a fallback.

Start in src/runtime/internal/navigation.ts at the linked title-handling logic, then use the StackBlitz reproduction to confirm the behavior for a frontmatter title of "Navigation". The change is done when an explicitly configured title remains visible while generated navigation titles and their fallbacks still behave as expected.