Compiled js warns about using 'eval'

[thislooksfun]

When I glanced at the compiled main.js file from the default theme it had the following at the top:

/*
 * ATTENTION: The "eval" devtool has been used (maybe by default in mode: "development").
 * This devtool is not neither made for production nor for readable output files.
 * It uses "eval()" calls to create a separate source file in the browser devtools.
 * If you are trying to read the output file, select a different devtool (https://webpack.js.org/configuration/devtool/)
 * or disable the default devtool with "devtool: false".
 * If you are looking for production-ready output files, see mode: "production" (https://webpack.js.org/configuration/mode/).
 */

This seems like not desirable behavior.

[Gerrit0]

PR welcome - that's definitely a mistake... I thought I had it configured to build in production when creating a release.