gebra <gebra-version> — no subject was resolved

tool error — no verdict was reached; this is not a verification result
  stage                   dispatch
  detail                  the run could not be assembled: no validator is registered for 
graph-well-formed. A run that checked the rest would be a weakened gate wearing a pass (§1.4 rule 
2), so no verdict is reported.

summary
  findings                0 fatal | 0 error | 0 warning
  notes                   0 carried (0 warning-grade)
  properties              none — the run reached no verdict for any property
  strict                  off
  exit                    2 — no verdict was reached
  snapshot                not recorded for this run: no verdict was reached
