Fix crash when MongoController connection fails

MongoView/Windows/DatabaseWindowController.swift

@@ -28,21 +28,23 @@ class DatabaseWindowController: NSWindowController {
     override func windowDidLoad() {
         super.windowDidLoad()
 
-        if mongoController == nil {
+        let setupMongo = mongoController == nil
+        if setupMongo {
             mongoController = MongoController(connectionString: "mongodb://localhost:27017")
-            mongoController.setup()
         }
         mongoController.statusDidChange.append({ [weak self] (status) in
             guard let self = self else { return }
             self.updateStatusText(status)
+            
+            if status == .success {
+                DispatchQueue.main.async {
+                    self.initializeUI()
+                }
+            }
         })
         self.updateStatusText(mongoController.status)
-
-        databaseViewController = DatabaseViewController(mongoController: mongoController)
-        contentViewController = databaseViewController
-        
-        if let initialCollection = initialCollection {
-            databaseViewController.showCollection(initialCollection)
+        if setupMongo {
+            mongoController.setup()
         }
 
         titleObservation = observe(\.contentViewController?.title) { [unowned self] (_, _) in
@@ -60,7 +62,7 @@ class DatabaseWindowController: NSWindowController {
     }
     
     private func updateWindowTitle() {
-        window?.title = databaseViewController.title ?? "MongoView"
+        window?.title = databaseViewController?.title ?? "MongoView"
     }
     
     private func updateStatusText(_ status: MongoController.Status) {
@@ -75,6 +77,15 @@ class DatabaseWindowController: NSWindowController {
         }
     }
 
+    private func initializeUI() {
+        databaseViewController = DatabaseViewController(mongoController: mongoController)
+        contentViewController = databaseViewController
+        
+        if let initialCollection = initialCollection {
+            databaseViewController.showCollection(initialCollection)
+        }
+    }
+    
 }
 
 extension NSToolbarItem.Identifier {