Replace cors module with a minimal working handler

micro-cors passes the preflight response to the server
handler which fails the request. There's a PR for this
that hasn't been merged/released.

package.json

@@ -9,7 +9,6 @@
     "apollo-server-micro": "^2.4.0",
     "graphql": "^14.1.1",
     "micro": "^9.3.3",
-    "micro-cors": "^0.1.1",
     "typescript": "^3.3.3"
   },
   "scripts": {

src/micro.ts

@@ -1,11 +1,18 @@
 import { ApolloServer } from 'apollo-server-micro'
-import cors from 'micro-cors'
 import { schema } from './graphql'
 
+const withCors: any = (handler: any) => (req: any, res: any, ...args: any) => {
+  if (req.method === 'OPTIONS')
+    res.end()
+  else {
+    return handler(req, res, ...args)
+  }
+}
+
 export const server = new ApolloServer({
   schema,
   introspection: true,
   playground: true
 })
 
-export default cors()(server.createHandler())
+export default withCors((server.createHandler()))

yarn.lock

@@ -2476,11 +2476,6 @@ methods@~1.1.2:
   version "1.1.2"
   resolved "https://registry.yarnpkg.com/methods/-/methods-1.1.2.tgz#5529a4d67654134edcc5266656835b0f851afcee"
 
-micro-cors@^0.1.1:
-  version "0.1.1"
-  resolved "https://registry.yarnpkg.com/micro-cors/-/micro-cors-0.1.1.tgz#af7a480182c114ffd1ada84ad9dffc52bb4f4054"
-  integrity sha512-6WqIahA5sbQR1Gjexp1VuWGFDKbZZleJb/gy1khNGk18a6iN1FdTcr3Q8twaxkV5H94RjxIBjirYbWCehpMBFw==
-
 micro@^9.3.2, micro@^9.3.3:
   version "9.3.3"
   resolved "https://registry.yarnpkg.com/micro/-/micro-9.3.3.tgz#32728c7be15e807691ead85da27fd8117a8bca24"