[Client] Handle connexion errors and invalid API responses

An alert is shown to the user and errors are logged to the console.
Also reformat the function code style.

truthseeker/static/js/api.js

@@ -1,28 +1,32 @@
-async function makeAPIRequest(endpoint, body){
+async function makeAPIRequest(endpoint, body) {
-    return new Promise((resolve, reject)=>{
+    return new Promise((resolve, reject) => {
         const fetchOptions = {
             method: "POST",
             body: new URLSearchParams(body)
+        };
+
+        fetch("/api/v1/" + endpoint, fetchOptions).then(response => {
+            const responseCode = response.status;
+            console.log(responseCode);
+            if (responseCode >= 500) {
+                reject("Error " + responseCode + " when fetching " + endpoint);
+                alert("Une réponse invalide du serveur a été obtenue, veuillez réessayer ultérieurement.");
+                return;
             }
-        fetch("/api/v1/"+endpoint, fetchOptions).then(resp => {
+
-            resp.json().then(jsonResp=>{
+            response.json().then(jsonResponse => {
-                if(jsonResp["error"] == 0){
+                if (jsonResponse["error"] === 0) {
-                    resolve(jsonResp)
+                    resolve(jsonResponse);
-                }else{
+                } else {
-                    reject(endpoint+": "+jsonResp["msg"])
+                    const message = jsonResponse["msg"];
+                    alert("Erreur du serveur : " + message);
+                    reject(endpoint + ": " + message);
                 }
             });
-        })
+        }).catch((e) => {
-    })
+            console.error("Failed to fetch API", e);
-}
+            alert("Une erreur est survenue lors de la connexion au serveur, veuillez vérifier votre connexion et / ou réessayer ultérieurement.");
-async function makeAPIImageRequest(endpoint, body){
+            reject(endpoint);
-    return new Promise((resolve, reject)=>{
+        });
-        const fetchOptions = {
+    });
-            method: "POST",
-            body: new URLSearchParams(body)
-        }
-        fetch("/api/v1/"+endpoint, fetchOptions).then(resp => {
-            resolve(resp)
-        })
-    })
 }