Throw runtime exception when trying to convert inexistend C++ object to Python
#if self.link_type != link_types.pointer:
text += "\n\t\tstatic " + self.name + "* get_py_obj(" + long_name + "* ref)\n\t\t{"
+ text += "\n\t\t\tif(ref == nullptr){"
+ text += "\n\t\t\t\tthrow std::runtime_error(\"" + self.name + " does not exist.\");"
+ text += "\n\t\t\t}"
text += "\n\t\t\t" + self.name + "* ret = (" + self.name + "*)malloc(sizeof(" + self.name + "));"
if self.link_type == link_types.pointer:
text += "\n\t\t\tret->ref_obj = ref;"