Adress case when nodal tag not found for csv writing

            self.nodalFilter.mesh = mesh

            op = NodalOP()

            try:

                self.nodalFilter.ApplyOnNodes(op)

            except IndexError:

                notFoundTags=set(self.nodalFilter.tags).difference(set(mesh.nodesTags.keys()))

                if len(notFoundTags):

                    raise Exception("Nodal Tag(s) not found in the mesh: ",list(notFoundTags))

                else:

                    emptyNodalTags=[tagname for tagname in self.nodalTags if len(mesh.nodesTags[tagname]) == 0]

                    raise Exception("Empty nodal tag(s) in mesh: ",emptyNodalTags)

            #conn = mesh.GetElementsOfType(op.name).connectivity[op.id,:]

            self.writeText("PointId")

            self.writeText(sep)