pub fn render_code_frame(
source: &str,
location: &CodeFrameLocation,
options: &CodeFrameOptions,
) -> Result<Option<String>>Expand description
Renders a code frame showing the location of an error in source code.
Returns Ok(None) when the location is out of range (e.g., the source is
empty or the start line exceeds the number of lines). This lets callers
distinguish “no code frame to show” from a genuine rendering error.