Class type identifier lookup in cmi triggers assertion

[dsheets]

class type ct = object
  method g : unit
end

class c : ct

results in

internal error, uncaught exception:
File "_build/lib-doc-ock/docOckIdentEnv.cml-native", line 239, characters 22-28: Assertion failed
Raised at file "_build/lib-doc-ock/docOckIdentEnv.cml-native", line 239, characters 22-34
Called from file "_build/lib-doc-ock/docOckCmi.cml-native", line 664, characters 16-46
Called from file "_build/lib-doc-ock/docOckCmi.cml-native", line 740, characters 16-60
Called from file "_build/lib-doc-ock/docOckCmi.cml-native", line 768, characters 6-56
Called from file "_build/lib-doc-ock/docOckCmi.cml-native", line 853, characters 17-56
Called from file "_build/lib-doc-ock/docOckCmi.cml-native", line 868, characters 14-46
Called from file "_build/lib-doc-ock/docOck.cml-native", line 174, characters 12-64
Called from file "_build/bin-codoc/codocCliExtract.ml", line 60, characters 12-30
Called from file "_build/bin-codoc/codocCliExtract.ml", line 144, characters 8-52
Called from file "_build/bin-codoc/codocCliExtract.ml", line 180, characters 6-64

[dsheets]

This issue is severe but not particularly common.