We added support for module and class type properties recently, and I think the issue here is that a previously existing property that included code incompatible with TorchScript is now failing to compile. There are two options:

Modify the property definition so that it is TorchScript compatible.
Exclude the property from compilation. This can be done by adding a class attributed named __ignored_properties__ and setting it to a list of the names of properties that should be ignored. You can see an example in this PR 10. In the same stack of PRs, there is another that enables the usual @ignore and @unused syntax work with properties, I plan to land that by the end of the week.