I figured out that node-sass dependency mentioned in web package is obsolete now.
I tried to change it to
"devDependencies": {
"@vue/cli-plugin-babel": "^3.0.0-rc.10",
"@vue/cli-plugin-eslint": "^3.0.0-rc.10",
"@vue/cli-service": "^3.0.0-rc.10",
"node-sass": "^4.14.0",
"sass-loader": "^7.0.3",
"vue-template-compiler": "^2.5.16"
},
then web-vue built successfully