Getting the OSM way id from lua used to work, but now I can’t get it to work anymore with v5.2.6. Using this way function:

function way_function (way, result)
  local id = way:id()
end

I get this error when extracting:

~/code/osrm-backend/sandbox$ (green_v5 *) ../build/osrm-extract mid.osm.pbf --profile ../profiles/testbot.lua
[info] Using script ../profiles/testbot.lua
[info] Input file: mid.osm.pbf
[info] Profile: testbot.lua
[info] Threads: 4
[STXXL-MSG] STXXL v1.4.1 (prerelease/Release)
[STXXL-ERRMSG] Warning: no config file found.
[STXXL-ERRMSG] Using default disk configuration.
[STXXL-MSG] Disk '/var/tmp/stxxl' is allocated, space: 1000 MiB, I/O implementation: syscall autogrow delete_on_exit queue=0 devid=0
[info] Parsing in progress..
[info] input file generated by 0.44.1
[info] timestamp: n/a
[info] Found no exceptions to turn restrictions
libc++abi.dylib: terminating with uncaught exception of type osrm::util::exception: ERROR occurred in profile script:
std::runtime_error: 'Trying to use unregistered class'
Abort trap: 6

scripting_environment.cpp does seem to link id() to an osmium method:

         luabind::class_<osmium::Way>("Way")
             .def("get_value_by_key", &osmium::Way::get_value_by_key)
             .def("get_value_by_key", &get_value_by_key<osmium::Way>)
             .def("id", &osmium::Way::id)
             .def("get_nodes", get_nodes_for_way, luabind::return_stl_iterator),

Am I missing something?