Added basic function for handling errors

main.js

@@ -12,9 +12,10 @@ clipboard.on('success', function (e) {
 });
 
 //Set default url
-chrome.tabs.query({ active: true, lastFocusedWindow: true }, tabs => {
+// chrome.tabs.query({ active: true, lastFocusedWindow: true }, tabs => {
-    document.getElementById("target").value = tabs[0].url;
+//     document.getElementById("target").value = tabs[0].url;
-});
+// });
+document.getElementById("target").value = "google.com";
 
 // Calls the api to create a new short url
 document.getElementById("create").onclick = createUrl;
@@ -35,7 +36,14 @@ function createUrl() {
             'Content-Type': 'application/json'
         })
     })
-            .then(res => res.json())
+        .then(res => {
+            if (!res.ok) {
+                handleError(res);
+            }
+            else {
+                res.json()
+            }
+        })
         .then(res => {
             document.getElementById("shorturl").innerText = res.url;
             document.getElementById("shorturl_container").className = "";
@@ -47,6 +55,22 @@ function createUrl() {
 
 }
 
+function handleError(res) {
+    if (res.status == 400) {
+        res.text().then((body)=>{
+            switch (body) {
+                case "Shortcode already exists, please choose another code":
+                    
+                    break;
+            
+                default:
+                    
+                    break;
+            }
+        })
+    }
+}
+
 //Resets the UI
 document.getElementById("reset").onclick = reset;
 function reset() {