fix: move `codemirror` to “external” config only

site/package.json

@@ -15,7 +15,6 @@
   },
   "dependencies": {
     "@polka/send": "^1.0.0-next.2",
-    "codemirror": "^5.44.0",
     "devalue": "^1.1.0",
     "do-not-zip": "^1.0.0",
     "express-session": "^1.15.6",

site/rollup.config.js

@@ -74,9 +74,12 @@ export default {
 			commonjs(),
 			json()
 		],
-		external: Object.keys(pkg.dependencies).concat(
+		external: [
+			'codemirror',
+			...Object.keys(pkg.dependencies || {}).concat(
 			require('module').builtinModules || Object.keys(process.binding('natives'))
-		),
+			)
+		]
 
 		// temporary, pending Rollup 1.0
 		experimentalCodeSplitting: true