lint: fix error reported by the linter

lntest/itest/lnd_test.go

@@ -11604,10 +11604,7 @@ func testSwitchOfflineDelivery(net *lntest.NetworkHarness, t *harnessTest) {
 	var predErr error
 	err = wait.Predicate(func() bool {
 		predErr = assertNumActiveHtlcs(nodes, numPayments)
-		if predErr != nil {
-			return false
-		}
-		return true
+		return predErr == nil
 	}, time.Second*15)
 	if err != nil {
 		t.Fatalf("htlc mismatch: %v", predErr)