improve error handling of webdavauth
improve error handling of webdavauth

cernbox/core,bluelml/core,bluelml/core,michaelletzgus/nextcloud-server,owncloud/core,michaelletzgus/nextcloud-server,IljaN/core,pollopolea/core,whitekiba/server,nextcloud/server,jbicha/server,owncloud/core,owncloud/core,bluelml/core,cernbox/core,pollopolea/core,cernbox/core,michaelletzgus/nextcloud-server,whitekiba/server,pixelipo/server,andreas-p/nextcloud-server,jbicha/server,nextcloud/server,andreas-p/nextcloud-server,pixelipo/server,sharidas/core,andreas-p/nextcloud-server,nextcloud/server,michaelletzgus/nextcloud-server,Ardinis/server,pmattern/server,lrytz/core,whitekiba/server,andreas-p/nextcloud-server,whitekiba/server,xx621998xx/server,pollopolea/core,xx621998xx/server,Ardinis/server,IljaN/core,jbicha/server,pmattern/server,phil-davis/core,IljaN/core,pixelipo/server,bluelml/core,endsguy/server,sharidas/core,IljaN/core,cernbox/core,pixelipo/server,IljaN/core,sharidas/core,lrytz/core,pmattern/server,pmattern/server,Ardinis/server,pixelipo/server,pollopolea/core,jbicha/server,endsguy/server,whitekiba/server,nextcloud/server,Ardinis/server,owncloud/core,lrytz/core,sharidas/core,pollopolea/core,endsguy/server,lrytz/core,sharidas/core,pmattern/server,xx621998xx/server,andreas-p/nextcloud-server,owncloud/core,endsguy/server,lrytz/core,cernbox/core,endsguy/server,xx621998xx/server,bluelml/core,xx621998xx/server,jbicha/server,Ardinis/server