add missing space in exception message (#2263)

a086b4b

Author: campersau

CefSharp.Wpf/ChromiumWebBrowser.cs

@@ -2159,7 +2159,7 @@ public void Load(string url)
         {
             if (!InternalIsBrowserInitialized())
             {
-                throw new Exception("The browser has not been initialized. Load can only be called" +
+                throw new Exception("The browser has not been initialized. Load can only be called " +
                                     "after the underlying CEF browser is initialized (CefLifeSpanHandler::OnAfterCreated).");
             }