LLVM validation error in flat_map

[jhass]

Okay, sorry for the issue title but I don't even...

array = [1, 2, [[3]]]
array.flat_map {|item| item.is_a?(Array) ? item : [item] of typeof(array)|typeof(array.first) }

Module validation failed: Function return type does not match operand type of return inst!
  ret %"(Array(Array(Array(Int32)) | Int32) | Array(Array(Int32)) | Array(Int32) | Int32)" %1, !dbg !45
 %"(Array(Array(Array(Int32)) | Int32) | Array(Array(Int32)) | Int32)" = type { i32, [1 x i64] }
???
???
???
???
???
__crystal_main
main
__libc_start_main
_start
???

https://carc.in/#/r/3p5k