Issue: Upgrading 4.1.0 Beta 2 Build 002 to Beta 4 Build 002 fails with "Call to a member function get_existing() on null"

#0 src/XF/Mvc/Entity/Entity.php(1208): vw_DM_Moderator_Controller_XF2->_postSave()
#1 src/addons/vw/vw/XF/Entity/EntityBase.php(556): XF\Mvc\Entity\Entity->save(false, false)
#2 src/addons/vw/vw/_core/controller/dm/xf2.php(369): vw\vw\XF\Entity\EntityBase->vwSave()
#3 src/addons/vw/vw/_install/lib/upgradepath/steps/4/1/0/beta/4/C/xf2.php(64): vw_DM_Controller_XF2->save()
#4 src/addons/vw/vw/Setup.php(299): vw_Install_UpgradePath_Steps_410beta4_C_Controller_XF2->{closure}(Object(vw\vw\Setup\Caller\Upgrade), false)
#5 src/addons/vw/vw/Setup.php(954): vw\vw\Setup->vwRunStep('upgrade', Object(vw_Install_UpgradePath_Steps_410beta4_C_Controller_XF2), Array, 1)
#6 src/XF/Admin/Controller/AddOn.php(576): vw\vw\Setup->upgrade(Array)
#7 src/XF/Mvc/Dispatcher.php(321): XF\Admin\Controller\AddOn->actionUpgrade(Object(XF\Mvc\ParameterBag))
#8 src/XF/Mvc/Dispatcher.php(248): XF\Mvc\Dispatcher->dispatchClass('XF:AddOn', 'Upgrade', Object(XF\Mvc\RouteMatch), Object(XF\Admin\Controller\AddOn), NULL)
#9 src/XF/Mvc/Dispatcher.php(100): XF\Mvc\Dispatcher->dispatchFromMatch(Object(XF\Mvc\RouteMatch), Object(XF\Admin\Controller\AddOn), NULL)
#10 src/XF/Mvc/Dispatcher.php(50): XF\Mvc\Dispatcher->dispatchLoop(Object(XF\Mvc\RouteMatch))
#11 src/XF/App.php(2178): XF\Mvc\Dispatcher->run()
#12 src/XF.php(390): XF\App->run()
#13 admin.php(13): XF::runApp('XF\\Admin\\App')
#14 {main}

Request state
array(4) {
  ["url"] => string(32) "/admin.php?add-ons/vw-vw/upgrade"
  ["referrer"] => string(63) "..../admin.php?add-ons/vw-vw/upgrade"
  ["_GET"] => array(1) {
    ["add-ons/vw-vw/upgrade"] => string(0) ""
  }
  ["_POST"] => array(7) {
    ["_xfProcessing"] => string(1) "1"
    ["continue"] => string(1) "1"
    ["confirm"] => string(1) "1"
    ["params"] => string(34) "{"step":1,"version_id":1214010022}"
    ["count"] => string(1) "2"
    ["finished"] => string(1) "0"
    ["_xfToken"] => string(8) "********"
  }
}

#0 src/addons/vw/vw/_core/controller/dm/moderator/xf2.php(15): vw\vw\Setup\View->handle_php_error(2, 'Declaration of ...', '/var/www/thetol...', 15, Array)
#1 src/addons/vw/vw/_hard/core.php(283): include('/var/www/thetol...')
#2 [internal function]: vw_Hard_Core::autoload('vw_DM_Moderator...')
#3 [internal function]: spl_autoload_call('vw_DM_Moderator...')
#4 src/addons/vw/vw/_core/controller/dm/vw.php(90): class_exists('vw_DM_Moderator...')
#5 src/addons/vw/vw/_install/lib/upgradepath/steps/4/1/0/beta/4/C/xf2.php(56): vw_DM_Controller->create('Moderator', 'SILENT')
#6 src/addons/vw/vw/Setup.php(299): vw_Install_UpgradePath_Steps_410beta4_C_Controller_XF2->{closure}(Object(vw\vw\Setup\Caller\Upgrade), false)
#7 src/addons/vw/vw/Setup.php(954): vw\vw\Setup->vwRunStep('upgrade', Object(vw_Install_UpgradePath_Steps_410beta4_C_Controller_XF2), Array, 1)
#8 src/XF/Admin/Controller/AddOn.php(576): vw\vw\Setup->upgrade(Array)
#9 src/XF/Mvc/Dispatcher.php(321): XF\Admin\Controller\AddOn->actionUpgrade(Object(XF\Mvc\ParameterBag))
#10 src/XF/Mvc/Dispatcher.php(248): XF\Mvc\Dispatcher->dispatchClass('XF:AddOn', 'Upgrade', Object(XF\Mvc\RouteMatch), Object(XF\Admin\Controller\AddOn), NULL)
#11 src/XF/Mvc/Dispatcher.php(100): XF\Mvc\Dispatcher->dispatchFromMatch(Object(XF\Mvc\RouteMatch), Object(XF\Admin\Controller\AddOn), NULL)
#12 src/XF/Mvc/Dispatcher.php(50): XF\Mvc\Dispatcher->dispatchLoop(Object(XF\Mvc\RouteMatch))
#13 src/XF/App.php(2178): XF\Mvc\Dispatcher->run()
#14 src/XF.php(390): XF\App->run()
#15 admin.php(13): XF::runApp('XF\\Admin\\App')
#16 {main}

Request state
array(4) {
  ["url"] => string(32) "/admin.php?add-ons/vw-vw/upgrade"
  ["referrer"] => string(63) ".../admin.php?add-ons/vw-vw/upgrade"
  ["_GET"] => array(1) {
    ["add-ons/vw-vw/upgrade"] => string(0) ""
  }
  ["_POST"] => array(7) {
    ["_xfProcessing"] => string(1) "1"
    ["continue"] => string(1) "1"
    ["confirm"] => string(1) "1"
    ["params"] => string(31) "{"step":9,"version_id":4010034}"
    ["count"] => string(2) "11"
    ["finished"] => string(1) "0"
    ["_xfToken"] => string(8) "********"
  }
}