textures don't work?

I tried getting a project up and running with the following code:

import createGame from 'voxel-engine'

const game = createGame({
    materials: [
        ['grass', 'dirt', 'grass_dirt'],
        'obsidian',
        'brick',
        'grass',
        'plank',
        'whitewool'
    ],
    texturePath: './textures/'
})

I already put all my textures in the correct folder and they are even loading properly in the browser. However, textures are not being displayed on the blocks (the player texture works but it's a bit buggy, note the black lines on the sides of the arms):

I also tried the exact code from the website, using browserify, it still did not work (same problems).

Any idea what could be wrong here?

BTW: I also have extreme FPS drops when flying around, even without any textures. there are also issues with chunks loading properly (see screenshot) - is this library still being developed at all?

Start at the createGame entry point and trace how the materials and texturePath options are loaded, comparing the provided example with the browserify version. Check why block textures differ from the working player texture, then separately investigate the reported FPS drops and chunk-loading problems. Done means the reported texture, performance, and chunk issues are reproduced and their causes are documented or fixed.