YAML parameters being interpreted as R and giving unhelpful error messages

Bug description

I believe you can put R commands into chunk paramters, this is useful but does give issues when you miss out a space. E.g.

---
title: "test"
---

```{r}
#| warning: false
#| eval:false
```

Which gives the error:

processing file: test.rmarkdown
Error in yaml::yaml.load(yaml, eval.expr = TRUE) :
Scanner error: while scanning a simple key at line 2, column 1 could not find expected ':' at line 3, column 1
Calls: .main ... parse_block -> partition_yaml_options ->
Execution halted

I presume that this is because the eval:false line is being interpreted as R rather than YAML, but the error message isn't helpful and had me messing with the top YAML as it didn't mention when code chunk it was referring to.

Strangely, dropping the warning line fixes things:

---
title: "test"
---

```{r}
#| eval:false
```

RStudio: 2022.02.3 Build 492
Windows

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