Runtime error (assert failed) on print tree

[basdp]

I get this weird error when parsing a toy language grammar:

output.s: /app/example.cpp:5116: void lexy::parse_tree<lexy::_br8>::builder::cancel_production(marker &&) [Reader = lexy::_br8, TokenKind = void, MemoryResource = void]: Assertion `_cur.prod' failed.

I have created a reproduction in the playground:
https://lexy.foonathan.net/playground/?id=o5G6631dW&mode=tree

It happens when you try to parse an expr_ident. Is this a bug in Lexy or did I do something wrong?
Apologies for not cleaning up the grammar, it could have been briefer.

[basdp]

As always, when you're stuck for hours, 5 minutes after posting the question, you solve it...
I removed the : lexy::transparent_production inheritance from expr_literal, which removed the error and allowed the parse_tree to run.

Still would like to know if it is a Lexy bug or if I just don't understand how to use lexy::transparent_production.

[foonathan]

Productions marked with lexy::transparent_production don't appear in the parse tree. This is definitely a bug, lexy should never fail with an assertion failure. (There are some cases where preconditions of grammar rules could be checked at compile-time, but it would be too complex to do so, so they're checked at runtime instead. You'll get a useful error messages then, however).

[foonathan]

The bug has now been fixed and your example works.