Clicking cheat before patients have spawned creates error

[sadger]

Clicking the spawn epidemic patient cheat before any patients have arrived causes the error below:

This was the error
Created game with savegame version 80.
Error in buttonup handler:
...orsixth\CorsixTH-epidemics\CorsixTH\Lua\hospital.lua:1240: attempt to index local 'patient' (a nil value)
stack traceback:
...orsixth\CorsixTH-epidemics\CorsixTH\Lua\hospital.lua:1240: in function 'createEpidemic'
...epidemics\CorsixTH\Lua\dialogs\resizables\cheats.lua:164: in function 'func'
...epidemics\CorsixTH\Lua\dialogs\resizables\cheats.lua:128: in function 'buttonClicked'
...epidemics\CorsixTH\Lua\dialogs\resizables\cheats.lua:95: in function 'callback'
...\corsixth\CorsixTH-epidemics\CorsixTH\Lua\window.lua:645: in function 'handleClick'
...\corsixth\CorsixTH-epidemics\CorsixTH\Lua\window.lua:1406: in function 'onMouseUp'
...\corsixth\CorsixTH-epidemics\CorsixTH\Lua\window.lua:1390: in function 'onMouseUp'
...ktop\corsixth\CorsixTH-epidemics\CorsixTH\Lua\ui.lua:703: in function <...ktop\corsixth\CorsixTH-epidemics\CorsixTH\Lua\ui.lua:690>
(tail call): ?
(tail call): ?
(tail call): ?
...top\corsixth\CorsixTH-epidemics\CorsixTH\Lua\app.lua:740: in function <...top\corsixth\CorsixTH-epidemics\CorsixTH\Lua\app.lua:735>

This is possibly because there is **no reception desk** as then there are no diseases to make epidemic, the cheat may be removed before release or at least tweaked. 

[sadger]

I have made sure you can only create a cheat epidemic with a reception desk in place with normal epidemics they can only start when players are spawning anyway. Needs testing.

[sadger]

Fixed.