Text substitution in the console throws errors

[xuv]

Maybe not a bug... or at least should pass over without breaking in case it happens.

If no argument is provided for string substitution, Stumpy returns an error and exists. Although the basic console will not complain. Maybe that behavior should be kept similar.
Test:

var Stumpy = require('stumpy');

var stumpy = Stumpy({
    replaceConsole: false
});

console.log('sleep %f hours', 8.21);
stumpy.log('sleep %f hours', 8.21');

console.log("sleep %f hours");
stumpy.log("sleep %f hours");