fix: 🐛 fixes an incorrect check for a string instead of regexp

[thkruz]

I previously thought we were looking for strings since we were converting them into regular expressions. It turns out we were passing in regular expressions and should have been typecasting them instead of creating new regular expressions out of the old ones.

[ajmas]

Actually there may be a small issue, since we are now loading the groups from the config.json, since here the regular expressions are strings and we haven't done any conversions to a RegExp. For this reason we should probably support both strings and RegExp, converting any string to RegExp:

    let regex: RexExp; 
    if (typeof this.data === 'string') {
      regex = new RegExp(this.data);
    } else if (this.data instanceof RegExp) {
      regex = this.data;
    } else {
      throw new Error('nameRegex must be a RegExp or a regex in string form');
    }