added more informative error message
added more informative error message

shaunharker/DSGRN,shaunharker/DSGRN,goullet/DSGRN,breecummins/DSGRN,goullet/DSGRN,breecummins/DSGRN,shaunharker/DSGRN,shaunharker/DSGRN,breecummins/DSGRN,shaunharker/DSGRN,shaunharker/DSGRN,shaunharker/DSGRN,breecummins/DSGRN,goullet/DSGRN,breecummins/DSGRN,goullet/DSGRN,goullet/DSGRN,goullet/DSGRN,breecummins/DSGRN,breecummins/DSGRN