Added cookie support

js/api.ts

@@ -1,12 +1,13 @@
-const prefix = document.getElementsByTagName("base")[0].href;
+const prefix = document.getElementsByTagName("base")[0].href.replace(/(?=.*)\/$/gm, "");
 
 
 async function unknownResponse(resp: Response): Promise<Error> {
-    let json = await resp.json()
+    let text = await resp.text()
     try {
+        let json = JSON.parse(text)
         return new Error(`${json["message"]} (${resp.status})`)
     } catch (error) {
-        return new Error(`Server sent unknown error: ${await resp.text()} (${resp.status})`)
+        return new Error(`Server sent unknown error: ${text} (${resp.status})`)
     }
 }
 
@@ -52,7 +53,8 @@ interface Asset {
 async function login(username: string, password: string): Promise<void> {
     let result = await fetch(`${prefix}/api/login`, {
         method: "POST",
-        body: JSON.stringify({"username": username, "password": password})
+        body: JSON.stringify({"username": username, "password": password}),
+        credentials: "include"
     })
     switch (result.status) {
         case 200: