ERR_INVALID_ARG_TYPE

[exside]

Just tried to install a11y to play around with it a little, but could not get anything to run, as soon as I try a11y <url> I get the following error:

child_process.js:397
    throw new ERR_INVALID_ARG_TYPE('file', 'string', file);
    ^

TypeError [ERR_INVALID_ARG_TYPE]: The "file" argument must be of type string. Received type object
    at normalizeSpawnArguments (child_process.js:397:11)
    at spawn (child_process.js:522:38)
    at execFile (child_process.js:218:15)
    at module.exports (/<path>/.nvm/versions/node/v10.4.1/lib/node_modules/a11y/index.js:33:5)
    at Immediate.eachAsync (/<path>/.nvm/versions/node/v10.4.1/lib/node_modules/a11y/cli.js:43:5)
    at runCallback (timers.js:697:11)
    at tryOnImmediate (timers.js:667:5)
    at processImmediate (timers.js:649:5)

On OS X with node 10.4.1.

Any idea what could go wrong here?