fix vim mode switch (codesandbox#129)

* fix vim mode switch

ugly hack to work around eslint dependency which redefines the require instance on window
this breaks the monaco loader.js
the following workaround can be removed after migration to monaco (vim mode) is done

* fix eslint overriding window.require reference

Author: johann-sonntagbauer

src/app/utils/codemirror/eslint-lint.js

@@ -354,7 +354,15 @@ export function fix(source: string) {
 }
 
 export default (async function initialize() {
-  if (!window.eslint && linter === null) {
+  // ugly hack to work around eslint dependency which redefines the require instance on window
+  // this breaks the monaco loader.js
+  // the following workaround can be removed after migration to monaco (vim mode) is done
+  const origRequire = window.require;
+  if (
+    !window.eslint &&
+    linter === null &&
+    !document.querySelector("script[src='/static/js/eslint.4.1.0.min.js']")
+  ) {
     // Add eslint as script
     const script = document.createElement('script');
     const src = '/static/js/eslint.4.1.0.min.js';
@@ -369,6 +377,8 @@ export default (async function initialize() {
     await delay(100);
   }
 
+  window.require = origRequire;
+
   linter = new window.eslint();
   linter.defineRules(allRules);
   CodeMirror.registerHelper('lint', 'javascript', validator);