Incorrect handling of OP_CONCAT.

[Uber]

Cause

Concat does not attempt to convert any objects, along with this table.concat does not call the proper metamethod.

Example:

local x = {}
setmetatable(x, {__concat = function(x, y) return '__concat' end})
print(''..x)
> invalid value (table) at index 2 in table for 'concat'

[Rerumu]

Issue fixed