Protocol Error @ Page.printToPDF

I’m getting the error below when running relaxed on a simple test file. This is a fresh vagrant box that I installed for relaxed, but I had the same issue in another box that I was using for development. Node is at version v11.30, npm at 6.4.1

I tried with one of the examples provided and got the same error.

Launching ReLaXed...

Processing /test.pug...
... HTML generated in 0.1s
... Document loaded in 0.1s
... Network idled in 0.2s
(node:18412) UnhandledPromiseRejectionWarning: Error: Protocol error (Page.printToPDF): Invalid parameters displayHeaderFooter: boolean value expected
    at Promise (/home/vagrant/.nvm/versions/node/v11.3.0/lib/node_modules/relaxedjs/node_modules/puppeteer/lib/Connection.js:186:56)
    at new Promise (<anonymous>)
    at CDPSession.send (/home/vagrant/.nvm/versions/node/v11.3.0/lib/node_modules/relaxedjs/node_modules/puppeteer/lib/Connection.js:185:12)
    at Page.pdf (/home/vagrant/.nvm/versions/node/v11.3.0/lib/node_modules/relaxedjs/node_modules/puppeteer/lib/Page.js:911:39)
    at Page.<anonymous> (/home/vagrant/.nvm/versions/node/v11.3.0/lib/node_modules/relaxedjs/node_modules/puppeteer/lib/helper.js:145:23)
    at exports.masterToPDF (/home/vagrant/.nvm/versions/node/v11.3.0/lib/node_modules/relaxedjs/src/masterToPDF.js:140:14)
    at process.internalTickCallback (internal/process/next_tick.js:77:7)
(node:18412) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 1)
(node:18412) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.