Fix problem where crictl tests would signal both error and done channels

PiperOrigin-RevId: 220372291
Change-Id: I054ba56a23c402c7244b476d7d6fe72084942a0e

runsc/test/testutil/crictl.go

@@ -212,6 +212,7 @@ func (cc *Crictl) run(args ...string) (string, error) {
 		output, err := cmd.CombinedOutput()
 		if err != nil {
 			errCh <- fmt.Errorf("error: \"%v\", output: %s", err, string(output))
+			return
 		}
 		done <- string(output)
 	}()