When return type of a nonterminal is unspecified, the plugin uses the toString() on the nonterminal name which leads to "LpNonterminalNameImpl({debug name})"

[dnbln]

Issue is here, when getTypeRef() returned null

[AzureMarker]

This definitely should be solved, but if there's action code then lalrpop can't infer the type, so it must be specified. This case is then a compile time lalrpop error.

[AzureMarker]

I think this is solved as of the above commit (or if that didn't catch it, then #17)