Second attempt: Try to disable external type-checker ... still no luck.

Author: DorianGrey

tests/e2e/tsconfig.json

@@ -1,5 +1,4 @@
 {
-  "extends": "../../tsconfig.json",
   "compilerOptions": {
     "target": "es5",
     "lib": ["es5", "dom"],

vue.config.js

@@ -33,18 +33,20 @@ module.exports = {
       .when(process.env.NODE_ENV === "production", config => {
         // Use a runtime chunk to optimize cache busting.
         // Otherwise, the runtime information would be added to the entry point.
-        config
-          .optimization
-          .runtimeChunk({ name: "runtime" });
+        if (!process.env.CYPRESS_ENV) {
+          config
+            .optimization
+            .runtimeChunk({ name: "runtime" });
+        }
 
-          // Configure path alias for rxjs.
-          const rxPaths = require("rxjs/_esm2015/path-mapping");
-          const rxResolvedPaths = rxPaths();
-          for (const p in rxResolvedPaths) {
-            if (rxResolvedPaths.hasOwnProperty(p)) {
-              config.resolve.alias.set(p, rxResolvedPaths[p]);
-            }
+        // Configure path alias for rxjs.
+        const rxPaths = require("rxjs/_esm2015/path-mapping");
+        const rxResolvedPaths = rxPaths();
+        for (const p in rxResolvedPaths) {
+          if (rxResolvedPaths.hasOwnProperty(p)) {
+            config.resolve.alias.set(p, rxResolvedPaths[p]);
           }
+        }
 
         // Configure style purging.
         const purgeOptions = {
@@ -82,6 +84,32 @@ module.exports = {
             return args;
           })
         ;
+
+        // Disable fork-ts-checker and switch ts-loader to also perform type checking.
+        // Some optimizations are not applied otherwise, thus...
+        // Unluckily, this means that we cannot use thread-loader for this ...
+        config
+          .plugins
+          .delete("fork-ts-checker");
+
+        config
+          .module
+          .rule("ts")
+          .uses
+          .delete("thread-loader");
+
+        config
+          .module
+          .rule("ts")
+          .use("ts-loader")
+          .options({
+            transpileOnly: false,
+            appendTsSuffixTo: [
+              "\\.vue$"
+            ],
+            happyPackMode: false,
+            allowTsInNodeModules: true
+          });
       });
   }
 };