I have added deno to the package for the moment at https://git.cloudron.io/cloudron/rocketchat-app/-/commit/7cbeed49142d7a7616b7c7f2ebe63c37a54b6d5f
But won't release a package yet, since I wasn't able to install any marketplace app due to various javascript exceptions thrown. But at least the deno error is gone. Strange system this.