using user_ldap_backend, enabling user_otp crashes owncloud 8.1.5

[DFWJim]

When using user_ldap_backend, as soon as I enable user_otp, owncloud 8.1.5 crashes. Going into the database (because I can't use the GUI to disable either app), only disabling user_otp makes the site work again. I get 500 errors from Apache, and this in the logs:

owncloud.log: {"reqId":"VpQxJhkDl6Z2C0LWJ4q8ogAAAAU","remoteAddr":"IPADDRESS_ON_MY_WORKSTATION","app":"PHP","message":"Argument 1 passed to OCA\user_ldap\USER_LDAP::__construct() must be an instance of OCA\user_ldap\lib\Access, none given, called in /var/www/html/owncloud/apps/user_otp/lib/otp.php on line 88 and defined at /var/www/html/owncloud/apps/user_ldap/user_ldap.php#52","level":3,"time":"2016-01-11T16:48:06-06:00"} {"reqId":"VpQxJhkDl6Z2C0LWJ4q8ogAAAAU","remoteAddr":"IPADDRESS_ON_MY_WORKSTATION","app":"PHP","message":"Argument 2 passed to OCA\user_ldap\USER_LDAP::__construct() must implement interface OCP\IConfig, none given, called in /var/www/html/owncloud/apps/user_otp/lib/otp.php on line 88 and defined at /var/www/html/owncloud/apps/user_ldap/user_ldap.php#52","level":3,"time":"2016-01-11T16:48:06-06:00"} {"reqId":"VpQxJhkDl6Z2C0LWJ4q8ogAAAAU","remoteAddr":"IPADDRESS_ON_MY_WORKSTATION","app":"PHP","message":"Undefined variable: access at /var/www/html/owncloud/apps/user_ldap/user_ldap.php#53","level":3,"time":"2016-01-11T16:48:06-06:00"} {"reqId":"VpQxJhkDl6Z2C0LWJ4q8ogAAAAU","remoteAddr":"IPADDRESS_ON_MY_WORKSTATION","app":"PHP","message":"Argument 1 passed to OCA\user_ldap\lib\BackendUtility::__construct() must be an instance of OCA\user_ldap\lib\Access, null given, called in /var/www/html/owncloud/apps/user_ldap/user_ldap.php on line 53 and defined at /var/www/html/owncloud/apps/user_ldap/lib/backendutility.php#35","level":3,"time":"2016-01-11T16:48:06-06:00"} {"reqId":"VpQxJhkDl6Z2C0LWJ4q8ogAAAAU","remoteAddr":"IPADDRESS_ON_MY_WORKSTATION","app":"PHP","message":"Undefined variable: ocConfig at /var/www/html/owncloud/apps/user_ldap/user_ldap.php#54","level":3,"time":"2016-01-11T16:48:06-06:00"} {"reqId":"VpQxJhkDl6Z2C0LWJ4q8ogAAAAU","remoteAddr":"IPADDRESS_ON_MY_WORKSTATION","app":"PHP","message":"Trying to get property of non-object at /var/www/html/owncloud/apps/user_ldap/user_ldap.php#226","level":3,"time":"2016-01-11T16:48:06-06:00"} {"reqId":"VpQxJhkDl6Z2C0LWJ4q8ogAAAAU","remoteAddr":"IPADDRESS_ON_MY_WORKSTATION","app":"PHP","message":"Call to a member function isCached() on a non-object at /var/www/html/owncloud/apps/user_ldap/user_ldap.php#226","level":3,"time":"2016-01-11T16:48:06-06:00"}

Errors from Apache: Jan 11 16:48:06 cloudserver portal[6563]: IP_ADDRESS_ON_LAN - - [11/Jan/2016:16:48:05 -0600] "POST /index.php/settings/ajax/enableapp.php HTTP/1.1" 200 20 "http://cloudserver.domain.com/index.php/settings/apps" "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/47.0.2526.106 Safari/537.36" Jan 11 16:48:06 cloudserver httpd[17170]: [:error] [pid 17170] [client IP_ADDRESS_ON_LAN:20504] PHP Fatal error: Call to a member function isCached() on a non-object in /var/www/html/owncloud/apps/user_ldap/user_ldap.php on line 226, referer: http://cloudserver.domain.com/index.php/settings/apps Jan 11 16:48:06 cloudserver portal[6563]: IP_ADDRESS_ON_LAN - - [11/Jan/2016:16:48:06 -0600] "GET /index.php/settings/ajax/navigationdetect.php?app=user_otp HTTP/1.1" 500 - "http://cloudserver.domain.com/index.php/settings/apps" "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/47.0.2526.106 Safari/537.36"

As soon as I disable user_otp from the database (in oc_appconfig, setting user_otp enabled no) the site works normally again.