Minor fixes and adjustments

src/math/Iterator3.zig

@@ -28,11 +28,11 @@ pub fn next(self: *@This()) ?Vector3 {
             next_current = next_current.setZ(next_current.getZ() + self.step.getZ());
             if (next_current.getZ() > self.max.getZ()) {
                 self.current = null;
-                return null;
+                return current;
             }
         }
     }
 
     self.current = next_current;
-    return next_current;
+    return current;
 }