eqwalize-all panics: contractivity.rs:320 'the stub should exist' (ConversionError(InvalidType))

[Taure]

elp eqwalize-all panics on a public OTP-29 rebar3 project, and elp lint on the same repo reports a related erlang-service failure.

Version

elp 1.1.0+build-2026-02-27 (linux x86_64)

Panic

thread '<unnamed>' panicked at crates/eqwalizer/src/ast/contractivity.rs:320:14:
the stub should exist, since expansion validation has already happened: ConversionError(InvalidType)

elp lint additionally reports:

src/banto_dep_audit.erl:1:1-1:1::[Error] [L0002] Could not parse, error: erlang service failed with: exception error: no case clause matching {unsafe,possibly}

which may share a root cause (the file uses the maybe expression).

Repro

git clone https://github.com/Taure/banto
cd banto && rebar3 compile && elp eqwalize-all

OTP 29, rebar3 project, deps include kura/bunko/gakudan/madoguchi (all on github). Happy to bisect to a minimal module if useful.

[robertoaloi]

@Taure Thanks for the report. I don't see any usages of maybe in the banto_dep_audit module (which should be supported anyway) and I don't seem able to reproduce. A minimal repro would be appreciated.

[penteract]

I get the same error running elp eqwalize simple when simple.erl contains

-module(simple).
loop(P) -> loop(P).

I'm using erlang/OTP 29. I've tested with builds from source at commits a7f4200 and 3d2b8af, and
with the elp-linux-x86_64-unknown-linux-gnu-otp-28.tar.gz build from the 2026-06-10 release (there doesn't seem to be an otp-29 build).