Reproduce Rstudio diagnostics spurious warnings

test.Rmd

---
title: "Untitled"
author: "test"
date: "17/7/2020"
output: html_document
---

```{r}
xy <- tibble::tibble(
  y = c(1, 2, 3, 4, 5, 6),
  x = 1:6
)
```

```{r}
1+2
```

```{r}
xy$z <- 2
xy$z[c(1,2,3)] <- 1
```