Don't let the user close the endpoint dialog window if the endpoint is an invalid URL

src/components/EndpointDialong.tsx

@@ -24,6 +24,10 @@ const EndpointDialog = ({ endpoint }: EndpointDialogProps) => {
   };
 
   const closeSettings = () => {
+    if (error) {
+      return;
+    }
+
     setOpen(false);
 
     setError(false);
@@ -78,9 +82,9 @@ const EndpointDialog = ({ endpoint }: EndpointDialogProps) => {
           />
         </DialogContent>
         <DialogActions>
-          <Button onClick={closeSettings}>Close</Button>
-
-          <Button onClick={() => {
+          <Button
+            disabled={error}
+            onClick={() => {
             if (isValidEndpoint()) {
               closeSettings();
               closeTheError();