Maybe try resolve or path.resolve?
extendWebpack (cfg) {
cfg.resolve.alias = {
...cfg.resolve.alias,
// Add your own alias like this
'vue$': 'vue/dist/vue.esm.js',
'@': resolve('src')
}
or…
extendWebpack (cfg) {
cfg.resolve.alias = {
...cfg.resolve.alias,
// Add your own alias like this
'vue$': 'vue/dist/vue.esm.js',
'@': path.resolve('src')
}