TOC title properties are inaccurately defined as empty strings

[phoenix-violeus]

The following ternary (lines 529-530 of epub.js) defines title as an empty string even when the given TOC title is truthy:

title = branch[i].navLabel && branch[i].navLabel.text || branch[i].navLabel===branch[i].navLabel ? '' : (branch[i].navLabel && branch[i].navLabel.text || branch[i].navLabel || "").trim();

Unless I'm mistaken, the solution is a simple matter of switching the expressions like so:

title = branch[i].navLabel && branch[i].navLabel.text || branch[i].navLabel===branch[i].navLabel ? (branch[i].navLabel && branch[i].navLabel.text || branch[i].navLabel || '').trim() : '';