tbl-subcap fails to render with only single element present

I have:

• searched the issue tracker for similar issues
• installed the latest version of Quarto CLI
• formatted my issue following the Bug Reports guide

Bug description

Rendering a document with a label and tbl-subcap with a single element causes a rendering error. Rendering succeeds if the label is removed or another tbl-subcap element is added.

Steps to reproduce

Attempt to render this document:

---
title: "test"
format: html
---

## Quarto table

```{r}
#| label: tbl-trivial
#| tbl-cap: "Trivial Caption" 
#| tbl-subcap:
#|  - "Trivial subcaption"
library(dplyr)
mtcars |> 
  head() |>
  knitr::kable()
```

Actual behavior

Attempting to render yields this error:

> quarto render test.qmd
- The project is out-of-sync -- use `renv::status()` for details.


processing file: test.qmd
1/3              
2/3 [tbl-trivial]
3/3              
output file: test.knit.md

pandoc 
  to: html
  output-file: test.html
  standalone: true
  section-divs: true
  html-math-method: mathjax
  wrap: none
  default-image-extension: png
  variables: {}
  
metadata
  document-css: false
  link-citations: true
  date-format: long
  lang: en
  title: test
  editor: visual
  
ERROR (/Applications/quarto/share/pandoc/datadir/_json.lua:212) unexpected character 'T' at line 1 col 1
Error running filter /Applications/quarto/share/filters/main.lua:
/Applications/quarto/share/pandoc/datadir/_json.lua:193: bad 'for' initial value (number expected, got nil)
stack traceback:
	/Applications/quarto/share/pandoc/datadir/_json.lua:407: in function '_json.decode'
	/Applications/quarto/share/filters/main.lua:17238: in local 'fn'
	/Applications/quarto/share/filters/main.lua:2927: in function </Applications/quarto/share/filters/main.lua:2921>
	(...tail calls...)
	...uarto/share/pandoc/datadir/../../filters/modules/jog.lua:34: in upvalue 'run_filter_function'
	...uarto/share/pandoc/datadir/../../filters/modules/jog.lua:223: in function <...uarto/share/pandoc/datadir/../../filters/modules/jog.lua:202>
	(...tail calls...)
	[C]: in function 'pandoc.List.map'
	...uarto/share/pandoc/datadir/../../filters/modules/jog.lua:125: in upvalue 'recurse'
	...uarto/share/pandoc/datadir/../../filters/modules/jog.lua:222: in local 'jogger'
	...uarto/share/pandoc/datadir/../../filters/modules/jog.lua:171: in upvalue 'recurse'
	...uarto/share/pandoc/datadir/../../filters/modules/jog.lua:222: in function <...uarto/share/pandoc/datadir/../../filters/modules/jog.lua:202>
	(...tail calls...)
	/Applications/quarto/share/filters/main.lua:572: in function </Applications/quarto/share/filters/main.lua:550>
	(...tail calls...)
	/Applications/quarto/share/filters/main.lua:1314: in local 'callback'
	/Applications/quarto/share/filters/main.lua:1332: in upvalue 'run_emulated_filter_chain'
	/Applications/quarto/share/filters/main.lua:1368: in function </Applications/quarto/share/filters/main.lua:1365>
WARN: Should not have arrived here:
ERROR: [non-error-thrown] undefined

Stack trace:
    at _Command.handleError (file:///Applications/quarto/bin/quarto.js:10032:117)
    at _Command.parseCommand (file:///Applications/quarto/bin/quarto.js:9719:12)
    at eventLoopTick (ext:core/01_core.js:178:7)
    at async quarto (file:///Applications/quarto/bin/quarto.js:175522:5)
    at async file:///Applications/quarto/bin/quarto.js:175550:5
    at async file:///Applications/quarto/bin/quarto.js:175405:14
    at async mainRunner (file:///Applications/quarto/bin/quarto.js:175407:5)
    at async file:///Applications/quarto/bin/quarto.js:175543:3

Expected behavior

I would expect the document to render successfully.

Your environment

MacOS Tahoe 26.0

Quarto check output

Quarto 1.8.24
[✓] Checking environment information...
      Quarto cache location: /Users/matthew/Library/Caches/quarto
[✓] Checking versions of quarto binary dependencies...
      Pandoc version 3.6.3: OK
      Dart Sass version 1.87.0: OK
      Deno version 2.3.1: OK
      Typst version 0.13.0: OK
[✓] Checking versions of quarto dependencies......OK
[✓] Checking Quarto installation......OK
      Version: 1.8.24
      Path: /Applications/quarto/bin

[✓] Checking tools....................OK
      TinyTeX: (not installed)
      Chromium: (not installed)

[✓] Checking LaTeX....................OK
      Tex:  (not detected)

[✓] Checking Chrome Headless....................OK
      Using: Chrome found on system
      Path: /Applications/Google Chrome.app/Contents/MacOS/Google Chrome
      Source: MacOS known location

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

[✓] Checking Python 3 installation....OK
      Version: 3.13.7
      Path: /opt/homebrew/opt/python@3.13/bin/python3.13
      Jupyter: (None)

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

[✓] Checking R installation...........OK
      Version: 4.5.1
      Path: /Library/Frameworks/R.framework/Versions/4.5-arm64/Resources
      LibPaths:
        - /Users/matthew/code/sandbox/support-122744/renv/library/macos/R-4.5/aarch64-apple-darwin20
        - /Users/matthew/Library/Caches/org.R-project.R/R/renv/sandbox/macos/R-4.5/aarch64-apple-darwin20/4cd76b74
      knitr: 1.50
      rmarkdown: 2.29

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