Sketcher: Fix void bounding box fall-through in constraint visualization

Add missing break after hiding rectangle points for a void bounding box,
preventing fall-through to CornerMin()/CornerMax() which would produce
undefined values.

src/Mod/Sketcher/Gui/EditModeConstraintCoinManager.cpp

@@ -832,6 +832,7 @@ Restart:
                             points[j].setValue(0.0f, 0.0f, 0.0f);
                         }
                         coords->point.finishEditing();
+                        break;
                     }
 
                     // 1. Get the original min/max points and dimensions