That would be parsed as a single operator and evaluated using the following rule:
> Evaluates to the operation defined for the operator in the environment. If none, evaluates to a constant function that pushes the operator, followed by all input terms, onto the output program.
What is the behavior of a program with unmatched braces? I am not sure a stray `}` would fit any of the defined syntax.
https://www.om-language.com/index.html#language__syntax__