getconstant

Returns one constant from a Lua function or stack level by one-based index. target must be a function or stack level number. Invalid stack levels raise “Level out of range”. Non-function and non-number targets raise a type error expecting “function or number”. C closures raise “Lua function expected”. Indexes below 1 raise “Constant index starts at 1”, and indexes past the available constants raise “Constant index out of range”. Function and table constants are returned as nil. debug.getconstant is an alias.