Python >= 3.8

[m-kuhn]

Since Python 3.8 I get

dictobject bad argument to internal function

When triggering a result. Assumption is a QVariant, sip, pyqt, python 3.8 compatibility problem.

[m-kuhn]

Assumption verified, modifying the locator result with a getter fixes the issue:

class CORE_EXPORT QgsLocatorResult
{
  public:
  [ ...]
    QVariant getUserData() { return userData; }
}

[m-kuhn]

Note: strange effects also happened with Python 3.6 (not exactly sure about the exception there, but it's also not functional)