Change the expectation for parsing an empty model.
Change the expectation for parsing an empty model.

hsorby/libcellml,cellml/libcellml,hsorby/libcellml,nickerso/libcellml,cellml/libcellml,nickerso/libcellml,nickerso/libcellml,cellml/libcellml,MichaelClerx/libcellml,MichaelClerx/libcellml,hsorby/libcellml,cellml/libcellml,nickerso/libcellml,hsorby/libcellml,MichaelClerx/libcellml