Return an empty dprior object if bayestopt_ is empty.

matlab/@dprior/dprior.m

@@ -61,7 +61,12 @@ classdef dprior < handle
         %
         % REQUIREMENTS
         % None.
-            if ~nargin % Empty object
+            if ~nargin
+                % Return an mpty object
+                return
+            end
+            if isempty(bayestopt_)
+                % Return an empty object
                 return
             end
             if isfield(bayestopt_, 'p1'), o.p1 = bayestopt_.p1; end