Fix dark mode for markers

src/css/ingame_hud/waypoints.scss

@@ -84,6 +84,8 @@
                 @include S(width, 15px);
                 @include S(height, 15px);
                 pointer-events: none;
+                // Double invert, to make sure it has the right color
+                @include DarkThemeInvert();
             }
         }
     }

src/js/game/shape_definition.js

@@ -223,7 +223,7 @@ export class ShapeDefinition extends BasicSerializableObject {
             layers.push(quads);
         }
 
-        if (layers.length === 0) {
+        if (layers.length === 0 || layers.length > 4) {
             return false;
         }