spat: Show signal groups without timing information

src/screen.rs

@@ -113,13 +113,15 @@ where
         .draw(target)?;
 
         // draw timing indicator
-        text::Text::with_alignment(
-            &alloc::format!("{}s", sig.min_end_sec),
-            geometry::Point::new(centerline, 160),
-            text_style,
-            text::Alignment::Center,
-        )
-        .draw(target)?;
+        if let Some(min_end_sec) = sig.min_end_sec {
+            text::Text::with_alignment(
+                &alloc::format!("{min_end_sec}s"),
+                geometry::Point::new(centerline, 160),
+                text_style,
+                text::Alignment::Center,
+            )
+            .draw(target)?;
+        }
     }
 
     Ok(())