Fix transit tube overlay rendering

src/tools/minimap.rs

@@ -468,7 +468,7 @@ impl<'a> GetVar<'a> for TypeRef<'a> {
 ///
 /// Every atom has a default sprite, which may be disabled, and a list of
 /// overlays.
-#[derive(Default, Debug, Clone)]
+#[derive(Debug, Clone)]
 pub struct Sprite<'s> {
     // filtering
     pub category: u32,  // type
@@ -511,6 +511,22 @@ impl<'s> Sprite<'s> {
     }
 }
 
+impl<'s> Default for Sprite<'s> {
+    fn default() -> Self {
+        Sprite {
+            category: 0,
+            icon: "",
+            icon_state: "",
+            dir: 0,
+            color: [255, 255, 255, 255],
+            ofs_x: 0,
+            ofs_y: 0,
+            plane: 0,
+            layer: 0,
+        }
+    }
+}
+
 fn category_of(path: &str) -> u32 {
     if path.starts_with("/area") {
         1