Revert "Better random (#213)"

This reverts commit c9f3644988.

common/util/random.ts

@@ -1,11 +1,7 @@
-// Returns a cryptographically random hexadecimal string of length `length`
-// (thus containing 4*`length` bits of entropy).
-export const randomString = (length = 12) => {
-  const bytes = new Uint8Array(Math.ceil(length / 2))
-  crypto.getRandomValues(bytes)
-  const hex = bytes.reduce((s, b) => s + ('0' + b.toString(16)).slice(-2), '')
-  return hex.substring(0, length)
-}
+export const randomString = (length = 12) =>
+  Math.random()
+    .toString(16)
+    .substring(2, length + 2)
 
 export function genHash(str: string) {
   // xmur3

functions/src/create-user.ts

@@ -42,7 +42,8 @@ export const createUser = functions
     const name = cleanDisplayName(rawName)
     let username = cleanUsername(name)
 
-    while (await getUserByUsername(username)) {
+    const sameNameUser = await getUserByUsername(username)
+    if (sameNameUser) {
       username += randomString(4)
     }