For those wanting (one way) to replicate the OP’s results:
julia> x + y = parse(Int, string(x, y))
+ (generic function with 1 method)
julia> typemax(Int16)
32767
julia> typemax(Int16) + 1
327671
(See this response and the post in general for more fun details: A most harrowing collection of Julia WATs - #10 by Philogicatician)