### Bug description

Using Quarto 1.3.340 on macOS

```bash
# Run in a brand new directory.
touch index.qmd
touch _quarto.yml
touch _metadata.yml
quarto render
#> ERROR: Internal Error: createSourceContext called with bad location.
#> 
#> Error: Internal Error: createSourceContext called with bad location.
#>     at createSourceContext (file:///Applications/RStudio.app/Contents/Resources/app/quarto/bin/quarto.js:14790:15)
#>     at createLocalizedError (file:///Applications/RStudio.app/Contents/Resources/app/quarto/bin/quarto.js:14864:28)
#>     at file:///Applications/RStudio.app/Contents/Resources/app/quarto/bin/quarto.js:15006:55
#>     at Array.map (<anonymous>)
#>     at ValidationContext.collectErrors (file:///Applications/RStudio.app/Contents/Resources/app/quarto/bin/quarto.js:15006:32)
#>     at ValidationContext.validate (file:///Applications/RStudio.app/Contents/Resources/app/quarto/bin/quarto.js:14929:21)
#>     at validate (file:///Applications/RStudio.app/Contents/Resources/app/quarto/bin/quarto.js:15293:20)
#>     at YAMLSchema.validateParse (file:///Applications/RStudio.app/Contents/Resources/app/quarto/bin/quarto.js:15318:34)
#>     at validate (file:///Applications/RStudio.app/Contents/Resources/app/quarto/bin/quarto.js:18623:43)
#>     at withValidator (file:///Applications/RStudio.app/Contents/Resources/app/quarto/bin/quarto.js:15381:25)
```

This can happen with an empty `_metadata.yml` at any position in a website hierarchy. I originally encountered this while preparing a directory structure to have sub-directory configuration overrides; I first created empty `_metadata.yml` files in each directory, but started experimenting with values in only one of the YAML files.

```

[✓] Checking versions of quarto binary dependencies...
      Pandoc version 3.1.1: OK
      Dart Sass version 1.55.0: OK
[✓] Checking versions of quarto dependencies......OK
[✓] Checking Quarto installation......OK
      Version: 1.3.340
      Path: /Applications/RStudio.app/Contents/Resources/app/quarto/bin

[✓] Checking basic markdown render....OK

[✓] Checking Python 3 installation....OK
      Version: 3.9.6
      Path: /Library/Developer/CommandLineTools/usr/bin/python3
      Jupyter: (None)

      Jupyter is not available in this Python installation.
      Install with python3 -m pip install jupyter

[✓] Checking R installation...........OK
      Version: 3.6.3
      Path: /Library/Frameworks/R.framework/Resources
      LibPaths:
        - /Library/Frameworks/R.framework/Versions/3.6/Resources/library
      knitr: 1.42.8
      rmarkdown: 2.20

[✓] Checking Knitr engine render......OK
```

### Checklist

- [X] Please include a minimal, fully reproducible example in a single .qmd file? Please provide the whole file rather than the snippet you believe is causing the issue.
- [X] Please [format your issue](https://quarto.org/bug-reports.html#formatting-make-githubs-markdown-work-for-us) so it is easier for us to read the bug report.
- [X] Please document the RStudio IDE version you're running (if applicable), by providing the value displayed in the "About RStudio" main menu dialog?
- [X] Please document the operating system you're running. If on Linux, please provide the specific distribution.
- [X] Please provide the output of `quarto check` so we know which version of quarto and its dependencies you're running.
cscheid
2023-05-18T15:53:38Z
aronatkins
bug
open
error with empty _metadata.yml file
https://github.com/quarto-dev/quarto-cli/issues/5600