different error message detail for previews of folder

[kiranparajuli589]

Describe the bug

While requesting to download previews of folder, error message detail is different in ocis than in oc10. For requests like downloading previews of another user, the error message pattern is the same as in the oc10 backend.

Steps to reproduce

• create a user test
• create a folder subfolder
• try to download preview of folder just made:

     curl -k https://localhost:9200/remote.php/dav/files/test/subfolder\?x\=32\&y\=32\&forceIcon\=0\&preview\=1 -u test:1234 -v | xmllint --format -

Response from oc10 backend

<?xml version="1.0" encoding="utf-8"?>
      <d:error xmlns:d="DAV:" xmlns:s="http://sabredav.org/ns">
        <s:exception>Sabre\DAV\Exception\BadRequest</s:exception>
        <s:message>Unsupported file type</s:message>
      </d:error>

Response from ocis backend

<?xml version="1.0" encoding="UTF-8"?>
  <d:error xmlns:d="DAV" xmlns:s="http://sabredav.org/ns"> 
    <s:exception>Sabre\DAV\Exception\BadRequest</s:exception>
    <s:message>{"id":"com.owncloud.api.thumbnails","code":400,"detail":"Unsupported file type","status":"Bad Request"}</s:message>
  </d:error>

Setup

ocis server started with following envs:

export OCIS_URL='https://localhost:9200' \
export STORAGE_HOME_DRIVER='ocis' \
export STORAGE_USERS_DRIVER='ocis' \
export STORAGE_DRIVER_OCIS_ROOT='/tmp/ocis/storage/users' \
export STORAGE_DRIVER_LOCAL_ROOT='/tmp/ocis/local/root' \
export STORAGE_DRIVER_OWNCLOUD_DATADIR='/tmp/ocis/owncloud/data' \
export STORAGE_METADATA_ROOT='/tmp/ocis/metadata' \
export STORAGE_HOME_DATA_SERVER_URL='http://localhost:9155/data' \
export STORAGE_USERS_DATA_SERVER_URL='http://localhost:9158/data' \
export WEB_UI_CONFIG=$HOME/www/ocConfigs/ocis-config.json \
export WEB_ASSET_PATH=$HOME/www/web/dist \
export IDP_IDENTIFIER_REGISTRATION_CONF=$HOME/www/ocConfigs/idp.yml \
export PROXY_ENABLE_BASIC_AUTH=True \
export OCIS_LOG_LEVEL='warn' \
export ACCOUNTS_DATA_PATH="/tmp/ocis-accounts/" \
export SETTINGS_DATA_PATH="/tmp/ocis/settings" \
export STORAGE_SHARING_USER_JSON_FILE="/tmp/ocis/shares.json" \

using either of the storage driver ocis or owncloud behaves the same way

Additional context

Previously #191