fix(graphical): render cause chains for inner errors

The default `GraphicalReportHandler` disables the printing of cause
chains for any inner errors (errors `related()` to a source diagnostic)
when it disables nested footer printing. This results in lost cause
chain information when printing with the default report handler.

src/handlers/graphical.rs

@@ -320,7 +320,6 @@ impl GraphicalReportHandler {
                         // Don't print footer for inner errors
                         let mut inner_renderer = self.clone();
                         inner_renderer.footer = None;
-                        inner_renderer.with_cause_chain = false;
                         inner_renderer.render_report(&mut inner, diag)?;
 
                         writeln!(f, "{}", self.wrap(&inner, opts))?;