Environments:

• Prettier Version: 3.9.4
• Running Prettier via: API
• Runtime: Node 24
• Operating System: macOS
• Prettier plugins (if any): prettier-plugin-solidity

Expected behavior:

when printing we ask comment.placement === 'ownLine' expecting a comment.placement to be a string.

Actual behavior:

comment.placement is undefined.

The interesting thing is that the value is still there after running addTrailingComment() so it must be deleted at some other moment.

I'd like to know if this behaviour is expected from now on.