Update TestEval test case "optional"

TestEval "optional" is broken. We should fix or remove.

```
    eval_test.go:169: Eval() got error = failed to compile the Expr expression: expected name (1:9)
         | object.?foo.orValue("fallback")
         | ........^, wantErr false
    --- FAIL: TestEval/optional (0.00s)
```