Fix build and redirect logged out users from '/create' to '/'

web/pages/create.tsx

@@ -1,5 +1,5 @@
 import router from 'next/router'
-import { useState } from 'react'
+import { useEffect, useState } from 'react'
 
 import { ContractsList } from '../components/contracts-list'
 import { Header } from '../components/header'
@@ -12,6 +12,10 @@ import { createContract } from '../lib/service/create-contract'
 export default function NewContract() {
   const creator = useUser()
 
+  useEffect(() => {
+    if (!creator) router.push('/')
+  })
+
   const [initialProb, setInitialProb] = useState(50)
   const [question, setQuestion] = useState('')
   const [description, setDescription] = useState('')
@@ -34,6 +38,8 @@ export default function NewContract() {
 
   const descriptionPlaceholder = `e.g. This market will resolve to “Yes” if, by June 2, 2021, 11:59:59 PM ET, Paxlovid (also known under PF-07321332)...`
 
+  if (!creator) return <></>
+
   return (
     <div>
       <Header />