Warning: Cannot read property 'rules' of undefined Use --force to continue.

[0815fox]

This happens, when the "options"-Object is empty:

tslint: {
    options: {},
    files: {
        src: [
            'src/ch.actifsource.cloud.*/**/*.ts'
        ]
    }
},

$ grunt tslint
Running "tslint:files" (tslint) task
Warning: Cannot read property 'rules' of undefined Use --force to continue.

Aborted due to warnings.

However, the warning is not very helpful. For the options object should be checked, that it is an object and that it contains a configuration property of type string, or other options, which are at least required, like e.g. 'rules'.
This will happen to everyone, who copies the first example from the overview section of README.md