Clean up and fixes

src/utils/sync-server.ts

@@ -58,10 +58,15 @@ export class SyncServer extends EventEmitter<SyncServerEventMap> {
    * @param identifier - The invitation identifier.
    * @returns The invitation.
    */
-  async getInvitation(identifier: string): Promise<XOInvitation> {
+  async getInvitation(identifier: string): Promise<XOInvitation | undefined> {
     // Send a GET request to the sync server
-    const response = await fetch(`${this.baseUrl}/invitations/${identifier}`);
-    const invitation = await response.json() as XOInvitation;
+    const response = await fetch(`${this.baseUrl}/invitations?invitationIdentifier=${identifier}`);
+    
+    if(!response.ok) {
+      throw new Error(`Failed to get invitation: ${response.statusText}`);
+    }
+    
+    const invitation = await response.json() as XOInvitation | undefined;
     return invitation;
   }
 
@@ -75,6 +80,9 @@ export class SyncServer extends EventEmitter<SyncServerEventMap> {
     const response = await fetch(`${this.baseUrl}/invitations`, {
       method: 'POST',
       body: encodeExtendedJson(invitation),
+      headers: {
+        'Content-Type': 'application/json',
+      },
     });
 
     // Throw is there was an issue with the request