fix(db): endless loop in UnwrapUntilPostgresError (#2010)

Ref: SRX-YNEAHU

pkg/db/transactions.go

@@ -172,15 +172,9 @@ func IsRetryablePostgresError(err error) bool {
 }
 
 func UnwrapUntilPostgresError(err error) *pq.Error {
-	for {
-		var pqErr *pq.Error
-		if errors.As(err, &pqErr) {
-			return pqErr
-		}
-		err2 := errors.Unwrap(err)
-		if err2 == nil {
-			// cannot unwrap any further
-			return nil
-		}
+	var pqErr *pq.Error
+	if errors.As(err, &pqErr) {
+		return pqErr
 	}
+	return nil
 }

pkg/db/transactions_test.go

@@ -92,3 +92,43 @@ func TestIsNotRetryableError(t *testing.T) {
 		})
 	}
 }
+
+func TestIsNotRetryableErrorEndlessLoop(t *testing.T) {
+	tcs := []struct {
+		InputCode         error
+		ExpectedRetryable bool
+	}{
+		{
+			InputCode:         fmt.Errorf("foobar"),
+			ExpectedRetryable: false,
+		},
+		{
+			InputCode:         fmt.Errorf("foobar1: %w", &pq.Error{Code: pq.ErrorCode("54000")}),
+			ExpectedRetryable: false,
+		},
+		{
+			InputCode:         fmt.Errorf("other1: %w", fmt.Errorf("foobar: %w", &pq.Error{Code: pq.ErrorCode("54000")})),
+			ExpectedRetryable: false,
+		},
+		{
+			InputCode:         fmt.Errorf("foobar2: %w", &pq.Error{Code: pq.ErrorCode("40000")}),
+			ExpectedRetryable: true,
+		},
+		{
+			InputCode:         fmt.Errorf("other2: %w", fmt.Errorf("foobar: %w", &pq.Error{Code: pq.ErrorCode("40000")})),
+			ExpectedRetryable: true,
+		},
+	}
+	for _, tc := range tcs {
+		tc := tc
+		t.Run(fmt.Sprintf("endless_loop_check_%s", tc.InputCode.Error()), func(t *testing.T) {
+			t.Parallel()
+
+			actualRetryable := IsRetryablePostgresError(tc.InputCode)
+
+			if diff := cmp.Diff(tc.ExpectedRetryable, actualRetryable); diff != "" {
+				t.Fatalf("error mismatch (-want, +got):\n%s", diff)
+			}
+		})
+	}
+}