Fix error cannot read property 'trim' of undefined in common.js file (Common.parseGenre)

[KHALED-LAKEHAL]

Common.parseGenre = function(origVal) {
// test value
if (typeof origVal === 'undefined') return [];
else {
// match everything inside parentheses
var split = origVal.trim().split(/((.*?))/g).filter(function(val) {
return val !== '';
});
var array = [];
for (var _i = 0, split_1 = split; _i < split_1.length; _i++) {
var cur = split_1[_i];
if (/^\d+$/.test(cur) && !isNaN(parseInt(cur, 10))) {
cur = ID3v1Parser_1.Genres[cur];
}
array.push(cur);
}
return array
.filter(function(val) {
return val !== undefined;
}).join('/');
}
};

[Borewit]

@AlgeriaSoft Maybe your intention was to send this pull request to music-metadata?