Greatly reduce repeated code

functions/api/infractions/new.ts

@@ -1,4 +1,5 @@
 import { GenerateUploadURL } from "../../gcloud.js";
+import { jsonError } from "../../common.js";
 
 const allowedFileTypes = [
   "image/gif",
@@ -17,36 +18,21 @@ export async function onRequestPost(context: RequestContext) {
       (p) => context.data.current_user.permissions & p,
     )
   )
-    return new Response('{"error":"Forbidden"}', {
-      headers: {
-        "content-type": "application/json",
-      },
-      status: 403,
-    });
+    return jsonError("Forbidden", 403);
 
   if (
     context.request.headers
       .get("content-type")
       ?.startsWith("multipart/form-data; boundary=")
   )
-    return new Response('{"error":"Invalid content type"}', {
-      headers: {
-        "content-type": "application/json",
-      },
-      status: 400,
-    });
+    return jsonError("Invalid content type", 400);
 
   let body: FormData;
 
   try {
     body = await context.request.formData();
   } catch {
-    return new Response('{"error":"Invalid form data"}', {
-      headers: {
-        "content-type": "application/json",
-      },
-      status: 400,
-    });
+    return jsonError("Invalid form data", 400);
   }
 
   if (
@@ -59,39 +45,21 @@ export async function onRequestPost(context: RequestContext) {
       "ban_unappealable",
     ].includes(body.get("punishment") as string)
   )
-    return new Response('{"error":"Invalid punishment"}', {
-      headers: {
-        "content-type": "application/json",
-      },
-      status: 400,
-    });
+    return jsonError("Invalid punishment", 400);
 
   if (!(body.get("user") as string).match(/^\d{17,19}$/))
-    return new Response('{"error":"Invalid user"}', {
-      headers: {
-        "content-type": "application/json",
-      },
-      status: 400,
-    });
+    return jsonError("Invalid user", 400);
 
   // @ts-expect-error
   const files: File[] = body.keys().find((key) => key.match(/^files\[\d]$/));
   const urlPromises = [];
   const origin = context.request.headers.get("Origin");
 
-  if (!origin)
-    return new Response('{"error":"Origin header missing"}', {
-      status: 400,
-    });
+  if (!origin) return jsonError("Origin header missing", 400);
 
   for (const file of files) {
     if (!allowedFileTypes.includes(file.type))
-      return new Response(`{"error":"File ${file.name} is not valid"}`, {
-        headers: {
-          "content-type": "application/json",
-        },
-        status: 415,
-      });
+      return jsonError(`File ${file.name} is not valid`, 415);
 
     const attachmentKey = `${Date.now()}${Math.round(
       Math.random() * 10000000,
@@ -111,12 +79,7 @@ export async function onRequestPost(context: RequestContext) {
   const settledURLPromises = await Promise.allSettled(urlPromises);
 
   if (settledURLPromises.find((p) => p.status === "rejected"))
-    return new Response('{"error":"Failed to process one or more files"}', {
-      headers: {
-        "content-type": "application/json",
-      },
-      status: 500,
-    });
+    return jsonError("Failed to process one or more files", 500);
 
   const infractionId = `${body.get(
     "user",