Show error screen on failed connection attempt

Encrypted Ink/Agent.swift

@@ -46,11 +46,19 @@ class Agent {
         }
     }
     
-    func connectWalletWithLink(_ link: String, account: Account) {
-        WalletConnect.shared.connect(link: link, address: account.address) { connected in
-            Window.closeAll()
-            Window.activateSafari()
-            // TODO: show error if failed to connect
+    func showErrorMessage(_ message: String) {
+        let windowController = Window.showNew()
+        windowController.contentViewController = ErrorViewController.withMessage(message)
+    }
+    
+    private func connectWalletWithLink(_ link: String, account: Account) {
+        WalletConnect.shared.connect(link: link, address: account.address) { [weak self] connected in
+            if connected {
+                Window.closeAll()
+                Window.activateSafari()
+            } else {
+                self?.showErrorMessage("Failed to connect")
+            }
         }
         
         let windowController = Window.showNew()

Encrypted Ink/Screens/ErrorViewController.swift

@@ -4,14 +4,24 @@ import Cocoa
 
 class ErrorViewController: NSViewController {
     
+    static func withMessage(_ message: String) -> ErrorViewController {
+        let new = instantiate(ErrorViewController.self)
+        new.message = message
+        return new
+    }
+    
+    private var message = ""
+    
     @IBOutlet weak var titleLabel: NSTextField!
     
     override func viewDidLoad() {
         super.viewDidLoad()
+        // TODO: show message text
     }
 
     @IBAction func actionButtonTapped(_ sender: Any) {
-        
+        Window.closeAll()
+        Window.activateSafari()
     }
     
 }