Function validate_frontmatter 

pub fn validate_frontmatter(
    fm: &Frontmatter,
    max_depth: usize,
    max: usize,
) -> Result<(), Error>

Validates a front matter structure against configured limits.

Checks:

• Maximum nesting depth.
• Maximum number of keys.
• Structure validity.

Arguments

• fm - Reference to the front matter to validate.
• max_depth - Maximum allowed nesting depth.
• max - Maximum allowed number of keys.

Returns

Ok(()) if validation passes, Error otherwise.

Errors

Returns Error if:

• The number of keys exceeds max.
• The nesting depth exceeds max_depth.