Still an issue here...
Reproduction Steps:
1. Started a fight in GE - 1 unit lost (a stealth tank) & won
2. go back to the city, start production of new stealth tank
3. Icon of production building idle - clicking it brings me to rogue hideout
4. All units in the hideout can be trained (got 3 on that hideout)
5. Start production of one of them
6. Game reports internal error and closes
7. When reentering the city, hideout has no free spaces (as expected)
Player: vircit
World: es1
Browser Version: Chrome 53.0.2785.116 (64-bit)*
Viewport Size: 1363 x 704*