No error when uploading a file in a deleted folder

[nono]

Hi,

reproduction steps:

• I open files in tab1, create a folder foo and go inside this folder
• I open files in tab2 and delete folder foo
• In tab1, I upload a file bar in the current folder (foo)
• The confirmation says it's a success
• In couchdb, the file is created, even if it's folder has been removed

expected:

• The upload fails with a message saying that it's impossible to upload a file in a folder that doesn't exist (anymore).
• (optional) The realtime socket can be used to put me at the root of files in tab1 when the current folder is deleted

[nono]

Oh, I think it's also possible to create a sub-folder in a removed folder.