Online media helpers (YouTubeHelper, VimeoHelper) preview images unusable in composer mode
When in composer mode, the online media helpers create preview images in locations like "./var/transient/youtube_1e65d7002154f3586b97bd19d2787829.jpg". But this files can't be accessed from e.g. "<f:image>" any longer, because "ResourceFactory::retrieveFileOrFolderObject()" wrongly returns a (non existing) folder object instead of file object. This is the case because "ResourceFactory::retrieveFileOrFolderObject()" uses "Environment::getPublicPath()" in behind but paths like "/var/transient/" are not public.
Steps to reproduce:
- Upload any youtube or vimeo video from backend
- Assign it to any record or model
- In FLUID, let it be rendered using "<f:image>" (when using "image" instead of "media" viewhelper, this automatically reads or creates the thumbnail)
This crashes the frontend.
Solution: Let the online media helpers create the preview images not inside "/var/transient" but in a real "public" path instead.