Improved error message on post fail

prs.desktop/Utils/PostUtils.cs

@@ -46,7 +46,7 @@ namespace PRSDesktop
                     }
                     if(successCount == 0)
                     {
-                        MessageBox.Show($"Processing failed: {string.Join('\n', failedMessages)}");
+                        MessageBox.Show($"Processing failed:\n - {string.Join("\n - ", failedMessages)}");
                     }
                     else if(failedMessages.Count == 0)
                     {
@@ -54,7 +54,7 @@ namespace PRSDesktop
                     }
                     else
                     {
-                        MessageBox.Show($"{successCount} items succeeded, but {failedMessages.Count} failed: {string.Join('\n', failedMessages)}");
+                        MessageBox.Show($"{successCount} items succeeded, but {failedMessages.Count} failed:\n - {string.Join("\n - ", failedMessages)}");
                     }
                     refresh();
                 }