This error occurs when you open a comment, but do not close it. 

Note that a comment started with '{' must be closed with '}', and a comment started with '(*' must be closed with '*)'.

program Produce;
(*Let's start a comment here but forget to close it
begin
end.

So the example just didn't close the comment.

program Solve;
(*Let's start a comment here and not forget to close it*)
begin
end.

Doing so fixes the problem.