Fix crash on recompile

[rpaladin]

Fixes crash that was first introduced in #2731

Steps to reproduce: Attempting to recompile (with cache) with zero export presets available caused crashing on build export.

Traceback (most recent call last):
  File "D:\Blender\Projects\RP\B3D_33\armsdk/armory\blender\arm\props_ui.py", line 1171, in invoke
    return self.execute(context)
  File "D:\Blender\Projects\RP\B3D_33\armsdk/armory\blender\arm\props_ui.py", line 1190, in execute
    make.play()
  File "D:\Blender\Projects\RP\B3D_33\armsdk/armory\blender\arm\make.py", line 572, in play
    compile(assets_only=(not wrd.arm_recompile))
  File "D:\Blender\Projects\RP\B3D_33\armsdk/armory\blender\arm\make.py", line 387, in compile
    item = wrd.arm_exporterlist[wrd.arm_exporterlist_index]
IndexError: bpy_prop_collection[index]: index 0 out of range, size 0