Paywalls: clean up the error view (#2873)

Tiny PR so I can feel like I'm contributing 😅 
Also helps me catch up with current status
| Before | After |
| :-: | :-: |
| ![Simulator Screenshot - iPhone 14 Pro - 2023-07-24 at 19 06
03](https://github.com/RevenueCat/purchases-ios/assets/3922667/2d6be10f-891a-48da-8c3f-0b0728438130)
| ![Simulator Screenshot - iPhone 14 Pro - 2023-07-24 at 19 05
26](https://github.com/RevenueCat/purchases-ios/assets/3922667/8b65c898-df9e-4fcd-bd0e-fc738652330d)
|

RevenueCatUI/Views/DebugErrorView.swift

@@ -70,11 +70,16 @@ struct DebugErrorView: View {
     private var errorView: some View {
         Text(self.description)
             .unredacted()
+            .padding()
             .fixedSize(horizontal: false, vertical: false)
             .background(
                 Color.red
                     .edgesIgnoringSafeArea(.all)
             )
+            .foregroundColor(.white)
+            .bold()
+            .cornerRadius(8)
+            .shadow(radius: 8)
     }
 
 }