docs: math.Vector2|3 zero vector normalisation raises

Author: elliot-100

docs/reST/ref/math.rst

@@ -281,7 +281,8 @@ Conversion can be combined with swizzling or slicing to create a new order
       | :sg:`normalize() -> Vector2`
 
       Returns a new vector that has ``length`` equal to ``1`` and the same
-      direction as self.
+      direction as self.  If the vector is the zero vector (i.e. has length
+      ``0`` thus no direction) a ``ValueError`` is raised.
 
       .. ## Vector2.normalize ##
 
@@ -291,7 +292,9 @@ Conversion can be combined with swizzling or slicing to create a new order
       | :sg:`normalize_ip() -> None`
 
       Normalizes the vector so that it has ``length`` equal to ``1``.
-      The direction of the vector is not changed.
+      The direction of the vector is not changed.  If the vector is the zero
+      vector (i.e. has length ``0`` thus no direction) a ``ValueError`` is
+      raised.
 
       .. ## Vector2.normalize_ip ##
 
@@ -770,7 +773,8 @@ Conversion can be combined with swizzling or slicing to create a new order
       | :sg:`normalize() -> Vector3`
 
       Returns a new vector that has ``length`` equal to ``1`` and the same
-      direction as self.
+      direction as self. If the vector is the zero vector (i.e. has length
+      ``0`` thus no direction) a ``ValueError`` is raised.
 
       .. ## Vector3.normalize ##
 
@@ -780,7 +784,8 @@ Conversion can be combined with swizzling or slicing to create a new order
       | :sg:`normalize_ip() -> None`
 
       Normalizes the vector so that it has ``length`` equal to ``1``. The
-      direction of the vector is not changed.
+      direction of the vector is not changed. If the vector is the zero vector
+      (i.e. has length ``0`` thus no direction) a ``ValueError`` is raised.
 
       .. ## Vector3.normalize_ip ##