fix some type errors

components/apiHelper.tsx

@@ -1,12 +1,10 @@
-function checkStatus(res) {
+function checkStatus(res: Response) {
   if (res.status < 200 || res.status >= 400) {
     throw new Error(`Something went wrong (Status ${res.status}) - I do feel very sorry!`)
   }
-
-  return res
 }
 
-export function generatePdf(state) {
+export async function generatePdf(state: Record<string, string>) {
   const options = {
     method: 'POST',
     headers: {
@@ -15,17 +13,19 @@ export function generatePdf(state) {
     body: JSON.stringify(state),
   }
 
-  return fetch('/api/pdf/generate/brief', options)
-    .then(checkStatus)
-    .then((res) => res.json())
+  const response = await fetch('/api/pdf/generate/brief', options)
+  checkStatus(response)
+  return response.json()
 }
 
-export function getLatest() {
-  return fetch('/api/pdf/latest')
-    .then(checkStatus)
-    .then((res) => res.json())
+export async function getLatest() {
+  const response = await fetch('/api/pdf/latest')
+  checkStatus(response)
+  return response.json()
 }
 
-export function removeLatest(item) {
-  return fetch(`/api/pdf/latest/${item.id}`, { method: 'DELETE' }).then(checkStatus)
+export async function removeLatest(item: { id: string }) {
+  const response = await fetch(`/api/pdf/latest/${item.id}`, { method: 'DELETE' })
+  checkStatus(response)
+  return response
 }