Check before attempting to remove released key

Author: eulertour

manim/renderer/opengl_renderer_window.py

@@ -48,7 +48,8 @@ def on_key_press(self, symbol, modifiers):
         self.renderer.scene.on_key_press(symbol, modifiers)
 
     def on_key_release(self, symbol, modifiers):
-        self.renderer.pressed_keys.remove(symbol)
+        if symbol in self.renderer.pressed_keys:
+            self.renderer.pressed_keys.remove(symbol)
         super().on_key_release(symbol, modifiers)
         self.renderer.scene.on_key_release(symbol, modifiers)