OS run feature help

I have just made OS for my use only. It has "Run program" feature.

Problem:

When i run program that has error with this feature, it will crash OS. Is there way to run startup always when program closes?

I will not give code, because i have meant it only for my use. If you dont know how to solve this without the code then you cant help me.

Look at that: http://www.lua.org/manual/5.1/manual.html#pdf-pcall

You can always pcall a loadstring.

There wasnt alot info about it, can someone explain me more about pcall?

Not really feeling like it. But the link grabie2 provided explains pretty much all there is to explain.

pcall is pretty simple: instead of calling function like that:

os.loadAPI("awesomeAPI")

you call it like that:

local ok, p1, p2, p3 = pcall(os.loadAPI, "awesomeAPI")
if not ok then
  errorMessage = p1
else
  --everything went OK
end

simple, huh?