Get Font Size returns 0.0 for default (null) font value

When using the default value in a "get text size" node, the height and width return 0.0.

Note: potentially returning null value as no hard value is presented to font.

James: Should use same fallback as other funcs that take a font

1. Open Editor (any project)
2. Create new HUD blueprint
3. Create a draw text node, plug the execution pin into an "event begin play" node
4. Create "get text size" node
5. plug width and height into x, y on draw text node
6. Create two print strings, plug width/height from get text size node into the two print strings (one for width, one for height)
7. In game mode (or create new game mode), set hud to new hud blueprint
8. compile all blueprints, save, and press play in editor