Tracing the broken inputs - how to get the rightmost failure?

[evilguest]

According to the documentation, the MatchResult is supposed to provide the rightmost fail position along with the list of expected rules at that position.
However, I have observed some confusing alterations of this behavior.
Consider the following grammar (I've tried to make it as short as possible to illustrate the case):

Foo {
  Program = Definition *
  Definition = 
  | Fun
  
  
  Fun = "fun" identifier "(" ")" Statements
  
  Statements = "{" Statement* "}"
  
  Statement (a statement) = 
  | Return
  
  Expression (an expression) = number | VarAccess 
  Return (a return statement) = "return" Expression ";"
  
  VarAccess (a variable) = identifier
  
  number (a constant) = digit+
  identifier = letter (alnum)*
}

Now I am trying to parse the following broken program:

fun a()
{
  quit;
}

Note that the quit statement is obviously wrong. Matching this input against the grammar above yields the following result:

Line 3,  col 3:
1 | fun a()
2 | {
3 |  quit;
     ^ 
4 | }
Expected "}" or a statement

So far, so good. But if we alter the grammar above with a supposedly innocent decoration - adding a description to the Fun rule - the result becomes much less funny:

Line 1,  col 1:
1 | fun a()
    ^
2 | {
Expected end of input

So, the matcher is no longer able to point me to the exact location of the problem. It reports it much further left in the source than it should.
Neither it lists all of the possible alternatives - it should tell me that it expects end of input OR a function definition.

So, the question is: how do I get the "right" rightmost failure without stripping off all the rule descriptions?

P.S. The ohm version I'm running is 17.1.0

Below is the complete grammar that produces this broken result:

Foo {
  Program = Definition *
  Definition = 
  | Fun
  
  
  Fun (a function definition) = "fun" identifier "(" ")" Statements
  
  Statements = "{" Statement* "}"
  
  Statement (a statement) = 
  | Return
  
  Expression (an expression) = number | VarAccess 
  Return (a return statement) = "return" Expression ";"
  
  VarAccess (a variable) = identifier
  
  number (a constant) = digit+
  identifier = letter (alnum)*
}

[gwhitney]

Duplicate of #302 and/or #544 - recommend closing in favor of those, although this example/use case should be kept in mind when addressing them.