cmisucp: catch the exception when getting CMIS object

Fixes crashers like the one when cancelling authentication request.
The error message are still not meaningful for the user, but this would
require libcmis API changes.

Change-Id: I22afbf4d39522a2b0dbd043a68dfef2b9308dcec

ucb/source/ucp/cmis/cmis_content.hxx

@@ -188,7 +188,7 @@ public:
         queryCreatableContentsInfo( const com::sun::star::uno::Reference< com::sun::star::ucb::XCommandEnvironment >& xEnv )
                 throw( com::sun::star::uno::RuntimeException );
 
-    libcmis::ObjectPtr getObject( );
+    libcmis::ObjectPtr getObject( ) throw ( libcmis::Exception );
 };
 
 }