Spamming escape while map is loading causes UI bug

[hexaflexahexagon]

Describe the bug
Spamming the escape key while loading a map from the console will occasionally bring you to the main menu with no elements besides the background and console. It is not a softlock because you can use ~ to bring the rest of the UI back. It can also happen while loading a map from the selector and occasionally can crash the game but I was not able to recreate either of these.

To Reproduce
Steps to reproduce the behavior:

1. Use the console to load a map map map_name
2. Spam the escape key while the map is loading
3. If the bug happens you will be met with a screen like this one:
   

Expected behavior
Ideally pressing escape at any time during the map loading sequence should instantly abort and return to the main menu. If this is not possible then pressing escape should simply do nothing until the map has finished loading, where it will then open the pause menu.

Desktop/Branch (please complete the following information):

• OS: Windows & Linux
• Branch: Steam 0.8.7 and 0.8.8-rc

Additional context
Reported by Lumia#7424 in Discord. https://discord.com/channels/235111289435717633/235125108656701440/808213970557206558