Multiple crash fixes:

• When a villager carrying something started to starve. (src/game/map.lua:378: attempt to index local 'grid' (a nil value))

• When a builder got a new directive, while being assigned to an untouched construction site. (src/game/constructioncomponent.lua:263: bad argument #1 to 'ipairs' (table expected, got nil))

• When choosing a new tile or building on certain platforms. (src/game/rendersystem.lua:316: attempt to compare number with nil)

• When reassigning a builder who was getting food. (src/game/constructioncomponent.lua:250: attempt to perform arithmetic on a nil value)

• When moving the camera on Android. (src/game/init.lua:583: attempt to index field 'dragging' (a nil value))