message: fix: ensure seedrandom is there when needed
  Fix an error when mirage is disabled in dev builds.
diff: @@ -147,7 +147,7 @@ module.exports = function(defaults) {
  test: 'vendor/ember/ember-template-compiler.js',
  });
  - if (mirageEnabled) {
  + if (mirageEnabled || !IS_PROD) {
  app.import('node_modules/seedrandom/seedrandom.min.js', {
  using: [{ transformation: 'amd', as: 'seedrandom' }],
  });
  