Workaround for issue webpack#1575

Author: samsam2310

lib/Server.js

@@ -132,6 +132,10 @@ function Server (compiler, options = {}, _log) {
   // eslint-disable-next-line
   const app = this.app = new express();
 
+  // ref: https://github.com/webpack/webpack-dev-server/issues/1575
+  // remove this when send@^0.16.3
+  express.static.mime.types["wasm"] = "application/wasm";
+
   app.all('*', (req, res, next) => {
     if (this.checkHost(req.headers)) {
       return next();