[2D][Tilemap] NullReferenceException in console when grid component is disabled and palette select tool is used

When grid component is disabled and palette select tool is used, hovering cursor over scene will cause NullReferenceException error to appear in console

Repro Steps:
1. Open sample scene, obeserve Grid component in Grid gameobject is disabled
2. Open Grid Palette window and click on Selection tool
3. Hover mouse over Scene view and observe error in console

Expected result: DrawGridMarquee should not be called when Grid component is disabled, no errors in console
Actual result: DrawGridMarquee is called when Grid component is disabled resulting in errors in console