In a Kotlin/JS project attempting to build fails on task

browserProductionWebpack

with

java.lang.NullPointerException (no error message)

This is my current config

kotlin {
    js(IR) {
        binaries.executable()
        browser {
            commonWebpackConfig {
                cssSupport {
                    enabled.set(true)
                    mode.set("extract")
                }
                devServer!!.port = 50517
            }
            testTask {
                useMocha()
            }
        }
    }
}

On a linux (kubuntu) system I have Firefox installed and no chrome/chromium. How can I solve this problem and are there any guides for setting up firefox to web testing