Function parse_string_with_errors 

pub fn parse_string_with_errors(source: &str) -> (Config, Vec<SyntaxError>)

Parse nginx configuration from a string, returning AST even when syntax errors exist.

Unlike parse_string, this function always produces a [Config] AST by leveraging rowan’s error-recovery. Syntax errors are returned alongside the AST so callers can report them without aborting the lint pipeline.