fix: ensure renderer is initialized before operations

- Add _ensure_initialized() method to Viewer3DWidget
- Queue pending meshes until widget is shown
- Add remove_mesh() method to PygfxRenderer
- Fix all viewer methods to check initialization

src/fluency/main.py

@@ -650,43 +650,62 @@ class Viewer3DWidget(QWidget):
         self._meshes: Dict[str, Any] = {}
         self._selected_normal: Optional[Tuple[float, float, float]] = None
         self._centroid: Optional[Tuple[float, float, float]] = None
+        self._pending_meshes: List[Tuple] = []
 
     def showEvent(self, event):
         if not self._initialized:
             self._renderer.initialize(self)
             self._initialized = True
+            for args in self._pending_meshes:
+                self.add_mesh(*args)
+            self._pending_meshes.clear()
             self._renderer.render()
 
+    def _ensure_initialized(self):
+        if not self._initialized:
+            self._renderer.initialize(self)
+            self._initialized = True
+
     def get_renderer(self) -> PygfxRenderer:
         return self._renderer
 
     def add_mesh(self, vertices, faces, color=None, name=None) -> str:
+        if not self._initialized:
+            self._pending_meshes.append((vertices, faces, color, name))
+            return f"pending_{len(self._pending_meshes)}"
+
+        self._ensure_initialized()
         mesh_id = self._renderer.add_mesh(vertices, faces, color, name)
         self._meshes[mesh_id] = {"vertices": vertices, "faces": faces, "name": name}
         self._renderer.render()
         return mesh_id
 
     def update_mesh(self, mesh_id: str, vertices, faces):
+        self._ensure_initialized()
         self._renderer.update_mesh(mesh_id, vertices, faces)
         self._meshes[mesh_id] = {"vertices": vertices, "faces": faces}
         self._renderer.render()
 
     def remove_mesh(self, mesh_id: str):
+        self._ensure_initialized()
         self._renderer.remove_mesh(mesh_id)
         if mesh_id in self._meshes:
             del self._meshes[mesh_id]
         self._renderer.render()
 
     def clear_scene(self):
+        self._ensure_initialized()
         self._renderer.clear_scene()
         self._meshes.clear()
         self._renderer.render()
 
     def fit_camera(self):
+        self._ensure_initialized()
         self._renderer.fit_camera()
         self._renderer.render()
 
     def set_camera_position(self, position, target):
+        self._ensure_initialized()
         self._renderer.set_camera_position(position, target)
         self._renderer.render()