Arithmetic in object declaration returns an error on build

[Bastien Botella]

Describe the bug
Bot fails to build when an arithmetic operation is given as object attribute.

To Reproduce

start:
  do a = 4
  do b = 2
  do foo = {
    "add": a + b
  }
  goto end

Expected behavior
It should build

[Francois Falala-Sechet]

Duplicate of #240, closing