Internal server error when trying to download a non-exist file

[ghost]

Steps to reproduce

1. Try to download a non-exist file. For example:
   http://10.211.55.9/nextcloud/index.php/apps/files_versions/download.php?file=../nonexistfile&revision=111
2. Internal server error appeared.
3. Check the log. There is an exception saying unable to getOwner

Expected behaviour

File not found

Actual behaviour

Internal server error

Server configuration

Operating system:
CentOS 7 x86_64
Linux 10.211.55.9 3.10.0-327.el7.x86_64 #1 SMP Thu Nov 19 22:10:57 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux

Web server:
httpd-2.4.6-40.el7.centos.4.x86_64

Database:
sqlite3

PHP version:
PHP 5.4.16 (cli) (built: Aug 11 2016 21:24:59)

Nextcloud version: (see Nextcloud admin page)
Nextcloud 10.0 (stable)

Updated from an older Nextcloud/ownCloud or fresh install:

Where did you install Nextcloud from:

Signing status:

List of activated apps:

The content of config/config.php:

Are you using external storage, if yes which one: local/smb/sftp/...

Are you using encryption: yes/no
no

Are you using an external user-backend, if yes which one: LDAP/ActiveDirectory/Webdav/...
no

Client configuration

Browser:
Firefox ESR 38.3.0

Operating system:
CentOS 7 x86_64

Logs

Web server error log

Nextcloud log (data/nextcloud.log)

Browser log

[nickvergessen]

@schiessle please have a look

[MorrisJobke]

Fix is in #2519