Exception when using "or"

``` haskell
-- throws Exception: Cannot process EGLess True
model :: FDModel
model = exists $ \col -> do
  [x1,x2,x3,x4] <- colList col 4
  allin col (cte 0,cte 5)
  x1 @<= x2
  x3 @>= x4
  x3 @>= x2 @|| x4 @<= x1 -- this causes the exception
  return col
```

I haven't tested it in other situations, this might be a corner case.
