[QA] Scenes | No in-world feedback when a scene fails to load due to broken code

### 🛠️ **Build version:**
Explorer v0.163.0-alpha-main

### 📔 **Issue Description:**
When a scene fails to load due to broken/erroring code, there is no in-world indication that the scene is broken versus intentionally empty. The parcel simply renders empty, with the only evidence of failure being in the in-game console (Errors tab), which is not clear or discoverable enough for most users. Confirmed with the team as a known issue with no existing ticket.

### 👣 **STR:**
1. Set up a scene where `src/index.ts` throws an error at runtime (e.g. `throw new Error('test')` at the top level)
2. Preview/enter the scene

### ✔️ **Expected Result:**
Some visible in-world warning or indicator should appear, letting the user know the scene failed to load due to an error, rather than leaving them to assume the parcel is just empty.

### ❌ **Actual Result with evidence:**
The parcel renders completely empty with no visual indication of failure. The error is only visible in the in-game console (Errors tab), which is easy to miss.

scene console:

```
[LOG] [17:20:57] [Log] SceneLog: UnityOpsApi initialized
[ERROR] [17:20:57] [Error] Error: Intentional test error
at src/index.ts (Script [19]:38:11) -> throw new Error("Intentional test error");
at __require (Script [19]:9:50)
at Script [19]:18951:26
at Script [19]:48170:4
at require (Script [20]:14:13)
at Script [22]:2:37
[ERROR] [17:20:57] [Error]
```

### ➗ **Reproduction:**
##### 🔁 Always - (reproduced consistently)

#### 🖥️ **Operative system and additional Notes:**
macOS, Apple M3 Pro. Confirmed with @nearnshaw: known issue, not related to the Bevy editor/renderer work — this is a general Explorer scene-loading UX gap.

https://github.com/user-attachments/assets/d890a083-b8a4-436e-83b3-d47f94232b18

[Player error scene.log](https://github.com/user-attachments/files/30605588/Player.error.scene.log)

Reproduce the failure with a scene whose src/index.ts throws at top level, then inspect the Explorer scene-loading flow and the in-game console Errors tab. Done means a broken scene produces a visible in-world warning or indicator instead of appearing indistinguishable from an intentionally empty parcel.

Written by the indexing model from the issue text.