Rules can parse with wrapping curly braces

[patrick-east]

Expected Behavior

A rule defined like:

{
    p := 123
}

Should not be valid according to the grammar we document

Actual Behavior

It parses fine, as long as there is only a single set of braces.. ex:

package example

{
    p := 123
}

q {
    p == 123
}

{12:18} /tmp ❯ opa eval -d ./x.rego -f pretty 'data'
{
  "example": {
    "p": 123,
    "q": true
  }
}

Additional Info

We should probably raise an error for this case. IMO it is somewhat confusing, and probably not what the author intended as the curly braces mean nothing to the language, they're essentially ignored.