Not implemented asserts to prevent silent fails

src/api/cocoa/mod.rs

@@ -268,6 +268,10 @@ impl Window {
             unimplemented!()
         }
 
+        // not implemented
+        assert!(win_attribs.min_dimensions.is_none());
+        assert!(win_attribs.max_dimensions.is_none());
+
         match opengl.robustness {
             Robustness::RobustNoResetNotification | Robustness::RobustLoseContextOnReset => {
                 return Err(CreationError::RobustnessNotSupported);