Destroying actors cause an exception

[realvictorprm]

Hi :)

This project is really great. I especially appreciate explicit mentioning of F# in the docs, this feels very inclusive :)

So in my baby steps trying out the engine I thought, what if I delete all actors and noticed that this simple code crashes the engine 😅

namespace REDACTED

open System
open System.Drawing
open UnrealEngine.Framework

type Logging =
    
    static member LogError(msg: String) = Debug.AddOnScreenMessage(5, 10.0f, Color.DarkRed, $"error: {msg}")
    static member LogError(ex: Exception) = Debug.AddOnScreenMessage(5, 10.0f, Color.DarkRed, $"error: {ex}")

module Main = // Indicates the main entry point for automatic loading by the plugin
    let OnWorldBegin() =
        Debug.AddOnScreenMessage(-1, 10.0f, Color.DeepPink, "Hello, Unreal Engine!")

    let OnWorldPostBegin() =
        Debug.AddOnScreenMessage(-1, 10.0f, Color.DeepPink, "How's it going?")

    let OnWorldEnd() =
        Debug.AddOnScreenMessage(-1, 10.0f, Color.DeepPink, "See you soon, Unreal Engine!")

    let OnWorldPrePhysicsTick(deltaTime:float32) =
        Debug.AddOnScreenMessage(1, 10.0f, Color.DeepPink, "On pre physics tick invoked!")

    let OnWorldDuringPhysicsTick(deltaTime:float32) =
        Debug.AddOnScreenMessage(2, 10.0f, Color.DeepPink, "On during physics tick invoked!")

    let OnWorldPostPhysicsTick(deltaTime:float32) =
        Debug.AddOnScreenMessage(3, 10.0f, Color.DeepPink, "On post physics tick invoked!")

    let OnWorldPostUpdateTick(deltaTime:float32) =
        Debug.AddOnScreenMessage(4, 10.0f, Color.DeepPink, "On post update tick invoked!")
        World.ForEachActor<Actor>(fun actor ->
            try
                actor.Destroy() |> ignore
            with ex -> Logging.LogError ex)

Error from Unreal Engine:

LoginId:08661cc64dadb273341ef1aa953b7ede
EpicAccountId:6ef538f8aa354d71b86c8fa9b1064244

Unhandled Exception: 0xe0434352

KERNELBASE
coreclr
coreclr
coreclr
System_Private_CoreLib
System_Private_CoreLib
System_Private_CoreLib
System_Private_CoreLib
System_Private_CoreLib
System_Private_CoreLib
System_Private_CoreLib
System_Private_CoreLib
System_Private_CoreLib
System_Private_CoreLib
System_Private_CoreLib
coreclr
coreclr
coreclr
ntdll
ntdll
ntdll
coreclr
coreclr
ntdll
ntdll
ntdll
KERNELBASE
coreclr
ntdll
coreclr
coreclr
coreclr
coreclr
coreclr
coreclr
coreclr
coreclr
UE4Editor_UnrealCLR!UnrealCLR::PostUpdateTickFunction::ExecuteTick() [H:\repositories\REDACTED\game\Plugins\UnrealCLR\Source\UnrealCLR\Private\UnrealCLR.cpp:1461]
UE4Editor_Engine
UE4Editor_Engine
UE4Editor_Core
UE4Editor_Core
UE4Editor_Core
UE4Editor_Engine
UE4Editor_Engine
UE4Editor_Engine
UE4Editor_Engine
UE4Editor_UnrealEd
UE4Editor_UnrealEd
UE4Editor
UE4Editor
UE4Editor
UE4Editor
UE4Editor
kernel32
ntdll

I just guess that one should not delete actors within that loop, however it would be good to somehow catch something like that or mention it in the docs here 🙈 Even an answer to this issue might be enough for the next person doing this 😂

[nxrighthere]

You are trying to destroy all actors in the world every tick when they are no longer valid in consecutive ticks after the initiated destruction which leads to the unhandled exception. On Linux and macOS unhandled exceptions terminate the editor, consider using try/catch blocks.

This code is also potentially unsafe because it might destroy hidden actors that are used by the engine itself.