Instructions for setting variables do not work

[AronBuzogany]

I have installed the package as suggested in the README and have the following version:

"sparqljs": "^3.7.1"

In the README it says that we can set the variables as such:

parsedQuery.variables = ['?mickey'];

But this gives me the following error:

object is undefined

By looking at the parsedQuery.variables array I have found that I could set the variable as such:

parsedQuery.variables = [{termType: "Variable", value: "mickey"}];