Improve FadeIn and FadeOut classes with error handling and type safety

manim/animation/fading.py

@@ -20,10 +20,9 @@
 ]
 
 import numpy as np
-from typing_extensions import Any
+from typing import Any, Union
 
 from manim.mobject.opengl.opengl_mobject import OpenGLMobject
-
 from ..animation.transform import Transform
 from ..constants import ORIGIN
 from ..mobject.mobject import Group, Mobject
@@ -56,25 +55,44 @@
         scale: float = 1,
         **kwargs: Any,
     ) -> None:
+
         if not mobjects:
-            raise ValueError("At least one mobject must be passed.")
+            raise ValueError("At least one mobject must be provided for fading.")
+
+        for mob in mobjects:
+            if not isinstance(mob, Mobject):
+                raise TypeError(f"Expected Mobject instances, got {type(mob)}")
+
         mobject = mobjects[0] if len(mobjects) == 1 else Group(*mobjects)
 
         self.point_target = False
+
         if shift is None:
             if target_position is not None:
                 if isinstance(target_position, (Mobject, OpenGLMobject)):
                     target_position = target_position.get_center()
-                shift = target_position - mobject.get_center()
+                elif not isinstance(target_position, np.ndarray):
+                    raise TypeError(
+                        "target_position must be a Mobject or np.ndarray"
+                    )
+                shift = np.array(target_position) - mobject.get_center()
                 self.point_target = True
             else:
                 shift = ORIGIN
+        else:
+            if not isinstance(shift, np.ndarray):
+                raise TypeError("shift must be of type np.ndarray")
+
+        if not isinstance(scale, (int, float)):
+            raise TypeError("scale must be a number")
+
         self.shift_vector = shift
         self.scale_factor = scale
+
         super().__init__(mobject, **kwargs)
 
     def _create_faded_mobject(self, fadeIn: bool) -> Mobject:
-        """Create a faded, shifted and scaled copy of the mobject.
+         """Create a faded, shifted and scaled copy of the mobject.
 
         Parameters
         ----------
@@ -86,16 +104,24 @@
         Mobject
             The faded, shifted and scaled copy of the mobject.
         """
-        faded_mobject: Mobject = self.mobject.copy()  # type: ignore[assignment]
+
+        faded_mobject = self.mobject.copy()  # type: ignore[assignment]
+
+        if not isinstance(faded_mobject, Mobject):
+            raise RuntimeError("Failed to create faded mobject copy.")
+
         faded_mobject.fade(1)
+
         direction_modifier = -1 if fadeIn and not self.point_target else 1
+
         faded_mobject.shift(self.shift_vector * direction_modifier)
         faded_mobject.scale(self.scale_factor)
+
         return faded_mobject
 
 
 class FadeIn(_Fade):
-    r"""Fade in :class:`~.Mobject` s.
+     r"""Fade in :class:`~.Mobject` s.
 
     Parameters
     ----------
@@ -143,7 +169,7 @@
 
 
 class FadeOut(_Fade):
-    r"""Fade out :class:`~.Mobject` s.
+     r"""Fade out :class:`~.Mobject` s.
 
     Parameters
     ----------
@@ -187,5 +213,9 @@
         return self._create_faded_mobject(fadeIn=False)
 
     def clean_up_from_scene(self, scene: Scene) -> None:
+        """Remove the mobject from the scene after fading out."""
         super().clean_up_from_scene(scene)
-        self.interpolate(0)
+        try:
+            self.interpolate(0)
+        except Exception as e:
+            raise RuntimeError(f"Error during cleanup interpolation: {e}")