Add case for zero vectors on angle_between_vectors

manimlib/utils/space_ops.py

@@ -152,6 +152,8 @@ def angle_between_vectors(v1: np.ndarray, v2: np.ndarray) -> float:
     """
     n1 = get_norm(v1)
     n2 = get_norm(v2)
+    if n1 == 0 or n2 == 0:
+        return 0
     cos_angle = np.dot(v1, v2) / (n1 * n2)
     return math.acos(clip(cos_angle, -1, 1))