Cleanup TipableVMobject: avoid mutable default and fix assign_tip_attr typo (#4503)

* Small touch-ups before fixing tip bugs
- fixed mutable default argument in Tipable VMobject constructor
- fixed typo in method name assign_tip_attr
- added two todo's which outline unexpected behavior in tip placement and how to solve

* refactor: align tip attr naming and remove TODO comments

---------

Co-authored-by: Benjamin Hackl <devel@benjamin-hackl.at>

Author: josiest

manim/mobject/geometry/arc.py

@@ -101,12 +101,12 @@ def __init__(
         self,
         tip_length: float = DEFAULT_ARROW_TIP_LENGTH,
         normal_vector: Vector3DLike = OUT,
-        tip_style: dict = {},
+        tip_style: dict | None = None,
         **kwargs: Any,
     ) -> None:
         self.tip_length: float = tip_length
         self.normal_vector = normal_vector
-        self.tip_style: dict = tip_style
+        self.tip_style: dict = tip_style if tip_style is not None else {}
         super().__init__(**kwargs)
 
     # Adding, Creating, Modifying tips
@@ -128,7 +128,7 @@ def add_tip(
         else:
             self.position_tip(tip, at_start)
         self.reset_endpoints_based_on_tip(tip, at_start)
-        self.asign_tip_attr(tip, at_start)
+        self.assign_tip_attr(tip, at_start)
         self.add(tip)
         return self
 
@@ -201,6 +201,7 @@ def position_tip(self, tip: tips.ArrowTip, at_start: bool = False) -> tips.Arrow
                 axis=axis,
             )  # Rotates the tip along the vertical wrt the axis
             self._init_positioning_axis = axis
+
         tip.shift(anchor - tip.tip_point)
         return tip
 
@@ -215,7 +216,7 @@ def reset_endpoints_based_on_tip(self, tip: tips.ArrowTip, at_start: bool) -> Se
             self.put_start_and_end_on(self.get_start(), tip.base)
         return self
 
-    def asign_tip_attr(self, tip: tips.ArrowTip, at_start: bool) -> Self:
+    def assign_tip_attr(self, tip: tips.ArrowTip, at_start: bool) -> Self:
         if at_start:
             self.start_tip = tip
         else:

manim/mobject/opengl/opengl_geometry.py

@@ -107,7 +107,7 @@ def add_tip(self, at_start: bool = False, **kwargs: Any) -> Self:
         """
         tip = self.create_tip(at_start, **kwargs)
         self.reset_endpoints_based_on_tip(tip, at_start)
-        self.asign_tip_attr(tip, at_start)
+        self.assign_tip_attr(tip, at_start)
         self.add(tip)
         return self
 
@@ -160,7 +160,7 @@ def reset_endpoints_based_on_tip(self, tip: OpenGLArrowTip, at_start: bool) -> S
         self.put_start_and_end_on(start, end)
         return self
 
-    def asign_tip_attr(self, tip: OpenGLArrowTip, at_start: bool) -> Self:
+    def assign_tip_attr(self, tip: OpenGLArrowTip, at_start: bool) -> Self:
         if at_start:
             self.start_tip = tip
         else: