Nested rich-text templates leads to item is undefined

[sebastianhutter]

Describe the issue that you're seeing. Any Loom videos or screenshots usually help a lot!

I have defined nested rich-text templates to create rows with a user-defined amount of columns.

(example md file with hugo short codes)

{{< row >}}
{{< col >}}
hello
{{< /col >}}

{{< col >}}
world
{{< /col >}}

{{< col >}}
!!!
{{< /col >}}
{{< /row >}}

Trying to open the nested col template in the tina-cms editor leads to the error message item is undefined

Reproduction

https://github.com/sebastianhutter/tina-cms-item-is-undefined

Steps to reproduce

Clone reproduction repository

Install hugo

Install node modules

npm i

Run the demo environment

npx tinacms dev -c "hugo server -D -p 1313 --bind 0.0.0.0"

Open http://localhost:1313/admin

Navigate to Posts -> Hello World

Open the embed Create row with columns

Open any of the Add column to row embeds

The error message item is undefined is shown

The rendered version of the hello world page can be accessed via http://localhost:1313/posts/hello-world

System Info

System:
    OS: macOS 14.4.1
    CPU: (10) arm64 Apple M1 Pro
    Memory: 1.39 GB / 32.00 GB
    Shell: 5.1.16 - /opt/homebrew/bin/bash
  Binaries:
    Node: 18.15.0 - ~/.nvm/versions/node/v18.15.0/bin/node
    Yarn: 1.22.22 - ~/Repository/private/tina-item-is-undefined/node_modules/.bin/yarn
    npm: 9.5.0 - ~/.nvm/versions/node/v18.15.0/bin/npm
  Browsers:
    Chrome: 124.0.6367.158
    Safari: 17.4.1
  npmPackages:
    @tinacms/cli: ^1.5.45 => 1.5.45 
    tinacms: ^1.6.3 => 1.6.3 

hugo v0.122.0

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