[de] Hyphen: Weird POS tags

I’m not sure if this has any consequences for the grammar checking, but I’m curious: Why has the hyphen ("-") these weird POS tags associated to it?

This is a known bug.
see Daniel’s comment from 20.12.2016 at [de] Some German verbs on the beginning of a sentences are identified only as substantives · Issue #635 · languagetool-org/languagetool · GitHub