a problem with custom post creation #258

Environment:

• Subreddit: r/mydevvitbottest2
• Devvit CLI: @devvit/cli/0.12.23-next-2026-05-05-17-20-47-e5daaf644.0
• @devvit/web: 0.12.23-next-2026-05-05-17-20-47-e5daaf644.0
• Node: v20.19.0

Problem:
Both reddit.submitCustomPost() and fallback reddit.submitPost() fail in playtest with:
Error: undefined undefined: undefined

This happens for:

1. submitCustomPost({ runAs: 'USER', entry: 'default', userGeneratedContent, textFallback })
2. submitCustomPost({ runAs: 'APP', entry: 'default', textFallback })
3. submitPost({ runAs: 'APP', text })

All post creation calls fail with the same gRPC error:

• GenericPluginClient.SubmitCustomPost
• GenericPluginClient.Submit

What I already tried

• Added permissions.reddit.asUser: ["SUBMIT_POST"] to devvit.json
• Uploaded a fresh version and explicitly installed queuecurb@0.0.2 to r/mydevvitbottest2
• Confirmed the local playtest CLI is already on 0.12.23-next
• Rebuilt and restarted playtest cleanly
• Verified the same failure happens for both USER and APP runs, and also for plain submitPost()