Agent panics when trying to persist a nil action

[AndersonQ]

When the agent tries to auto unenroll due too many authentication failures, the unenroll handler sets the action to nil before saving it. However the state store panics when setting a nil action.

• the handler sets the action to nil:

  • elastic-agent/internal/pkg/agent/application/actions/handlers/handler_action_unenroll.go

    Lines 86 to 89 in b4877f5

    	if action.IsDetected {
    	// not from Fleet; so we set it to nil so policyChange doesn't ack it
    	a = nil
    	}

• the handler tries to save the action

  • elastic-agent/internal/pkg/agent/application/actions/handlers/handler_action_unenroll.go

    Lines 95 to 101 in b4877f5

    	if h.stateStore != nil {
    	// backup action for future start to avoid starting fleet gateway loop
    	h.stateStore.SetAction(a)
    	if err := h.stateStore.Save(); err != nil {
    	h.log.Warnf("Failed to update state store: %v", err)
    	}
    	}

• the store tries to access properties of a nil pointer

  • elastic-agent/internal/pkg/agent/storage/store/state_store.go

    Lines 183 to 188 in b4877f5

    	default:
    	s.log.Debugw("trying to set invalid action type on the state store, ignoring the action",
    	"action.type", a.Type(),
    	"action.id", a.ID())
    	}
    	}