### Bug description

For a blog with a default post listing, if one of the posts has a badge as only image, the badge is used as image in the listing. 

I was surprised by this behavior but it might be intended?

![image](https://github.com/quarto-dev/quarto-cli/assets/8360597/03d1d52c-0364-4a4f-b896-5d00b5a5b95a)


### Steps to reproduce

https://github.com/maelle/badgeblog/blob/fadf0dc478982e8fff2f8ec186432de951590875/posts/post-with-code/index.qmd#L8

### Expected behavior

I would expect no image to be used (except for a placeholder image if one was defined).

### Actual behavior

_No response_

### Your environment

- RStudio 2023.03.0+386 "Cherry Blossom" Release (3c53477afb13ab959aeb5b34df1f10c237b256c3, 2023-03-09) for Ubuntu Bionic
Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) rstudio/2023.03.0+386 Chrome/108.0.5359.179 Electron/22.0.3 Safari/537.36

### Quarto check output

```bash
[✓] Checking versions of quarto binary dependencies...
      Pandoc version 2.19.2: OK
      Dart Sass version 1.32.8: OK
[✓] Checking versions of quarto dependencies......OK
[✓] Checking Quarto installation......OK
      Version: 1.3.49
      Path: /opt/quarto/bin

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

[✓] Checking Python 3 installation....OK
      Version: 3.8.10
      Path: /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: 4.2.0
      Path: /opt/R/4.2.0/lib/R
      LibPaths:
        - /home/maelle/R/x86_64-pc-linux-gnu-library/4.2
        - /opt/R/4.2.0/lib/R/library
      rmarkdown: 2.22

[✓] Checking Knitr engine render......OK
```
dragonstyle
2023-07-03T07:30:11Z
maelle
bug
closed
Should a badge be used as image in a post listing
https://github.com/quarto-dev/quarto-cli/issues/6091