Refactor exception usage

src/util/list.ts

@@ -1,6 +1,6 @@
 /*
  * server component for the TimeLimit App
- * Copyright (C) 2019 Jonas Lochmann
+ * Copyright (C) 2019 - 2020 Jonas Lochmann
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as
@@ -17,18 +17,6 @@
 
 import { uniq } from 'lodash'
 
-export function assertNonEmptyListWithoutDuplicates (list: Array<string>) {
-  if (list.length === 0) {
-    throw new Error('expected not empty list')
-  }
-
-  if (uniq(list).length !== list.length) {
-    throw new Error('expected list without duplicates')
-  }
-}
-
-export function assertListWithoutDuplicates (list: Array<string>) {
-  if (uniq(list).length !== list.length) {
-    throw new Error('expected list without duplicates')
-  }
+export function hasDuplicates (list: Array<string>): boolean {
+  return uniq(list).length !== list.length
 }