rmarkdown error "attempt to use zero-length variable name" : <p>When i generate a new rmarkdown file (or open existing rmarkdown-files) and try to run a rmarkdown chunk, i get this error: "Error: attempt to use zero-length variable name".
I have Win10 and did a fresh install of R and Rstudio yesterday. What did i miss? Where does this error come from?</p>

<pre><code>```{r cars}
summary(cars)
```
</code></pre>

<blockquote>
  <p>```{r cars}
  Error: attempt to use zero-length variable name</p>
</blockquote>

<p><a href="https://i.stack.imgur.com/FqebP.png" rel="noreferrer"><img src="https://i.stack.imgur.com/FqebP.png" alt="enter image description here"></a></p>
