Add server only to restrict things properly, starting on Prisma setup.

src/graphql/schema.ts

@@ -1,3 +1,4 @@
+import 'server-only';
 import { gql } from 'apollo-server-micro';
 import { gameTypeDefs, gameResolvers } from './game';
 import { mergeTypeDefs } from '@graphql-tools/merge';