global map cell size can crash openmw if set to too high a value

I haven't played in a few weeks so I couldn't say which commit caused this, but as of a while ago the game won't load for me past the menus. You can hear the world's sound (Water and all that) for a second or two, then it stutters for a couple seconds and CTDs.

[15:13:57.521 W] RenderStage::runCameraSetUp(), FBO setup failed, FBO status= 0x8cd6
[15:13:58.258 W] ContextData::incrementContextIDUsageCount(0) to 2
[15:14:00.181 W] RenderStage::runCameraSetUp(), FBO setup failed, FBO status= 0x8cd6
[15:14:05.628 W] ContextData::incrementContextIDUsageCount(0) to 3

• OS: Ubuntu Focal, with an AMD Radeon 3 3200 APU.
• Version: PPA's latest
• What are the exact steps to reproduce the problem? Try to start a new game.

PS: It'd be good, for these situations, if the ppa had more than the very last version. One a week for the last three or four weeks maybe? Just a stray thought.