TL;DR

• Verify the permissions and configuration of the custom plan directory to ensure it allows writing nested files.

Guidance

• Check the directory structure and permissions of the custom plan directory to identify any restrictions on writing nested files.
• Review the documentation or configuration options for the extension to see if there are any specific settings or flags that need to be enabled to allow writing nested files.
• Test writing a file directly in the custom plan directory to isolate if the issue is specific to nested files or a broader permission issue.

Notes

• The exact solution may depend on the specific extension and its configuration, which is not provided in the issue.
• Additional information about the extension, its version, and the environment it's running in could help narrow down the cause.

Recommendation

• Apply workaround: Modify the extension's configuration or the custom plan directory's permissions to allow writing nested files, as this seems to be the most direct approach to resolving the issue given the information available.