Invalid(?) pin fails silently

[thisismydesign]

This creates a link in head:

pin 'tom-select', to: '/folder/tom-select/dist/esm/tom-select.complete.js'

But neither of these does anything and there is no indication of anything being wrong:

pin 'tom-select', to: './folder/tom-select/dist/esm/tom-select.complete.js'
pin 'tom-select', to: 'folder/tom-select/dist/esm/tom-select.complete.js'

Could there be an indication when the pin fails to create an output?