vacuum's got_error: compare against error code, not against the state (#379)

Breaking change. `got_error` returns now True even after the state has been changed (e.g. the vacuum went to idle) but the error is still present.

Author: rytilahti

miio/vacuumcontainers.py

@@ -139,7 +139,7 @@ def is_on(self) -> bool:
     @property
     def got_error(self) -> bool:
         """True if an error has occured."""
-        return self.state_code == 12
+        return self.error_code != 0
 
     def __repr__(self) -> str:
         s = "<VacuumStatus state=%s, error=%s " % (self.state, self.error)