Key already exists exception when enter play mode options is on in 1.5.2

[Xajaxaja]

Description

A blank unity project with enter play mode options enabled and domain reload off, throws an exception for every network behavior in the project.

The stack-trace highlights even built in network behaviors like networkanimator or networktransform.

ArgumentException: An item with the same key has already been added. Key: 1665640498
System.Collections.Generic.Dictionary`2[TKey,TValue].TryInsert (TKey key, TValue value, System.Collections.Generic.InsertionBehavior behavior) (at <eef08f56e2e042f1b3027eca477293d9>:0)
System.Collections.Generic.Dictionary`2[TKey,TValue].Add (TKey key, TValue value) (at <eef08f56e2e042f1b3027eca477293d9>:0)
Unity.Netcode.Components.NetworkAnimator.InitializeRPCS_NetworkAnimator () <0x26f88a73b30 + 0x000ca> in <b476fa4747044164bbf4bd8f8f4d4d2e>:0

A clear and concise description of what the bug is.

Reproduce Steps

1. Create a blank unity project in 2022.3.5f1 (URP core)
2. Install netcode for game objects version 1.5.2
3. Install parallel sync via github link https://github.com/VeriorPies/ParrelSync.git?path=/ParrelSync
4. Go to project settings and enable "Enter Play Mode Options", ensure that "Reload Domain" is off.
5. Enter play mode once, then exit.
6. Enter play mode again and 2 exceptions should appear. One for NetworkTransform and one for NetworkAnimator.

Actual Outcome

No error

Expected Outcome

One exception for each networkbehavior in the project.

Screenshots

Environment

• OS: Windows 10
• Unity Version: 2022.3.5f1
• Netcode Version: 1.5.2

Additional Context

Error does not appear if the netcode version is downgraded to 1.4.0, or 1.5.1

[slaff23]

I have same errors after updating unity version from 2022.1.23f1 to newest alpha version 2023.2.0a22 including updating netcode for game objects to 1.5.2.

The errors also appear when creating a clean new project with unity alpha version 2023.2.0a22 and only installing netcode for gameobjects 1.5.2 without ParrelSync.

Reproduce Steps

1. Create new project - in my case 2D (URP)
2. Install package "Netcode for GameObjects 1.5.2"
3. Activate "Enter Play Mode Options" under Editor tab without reload of domain and scene
   
4. Click Play --> Errors do not appear
5. Click Stop and Play again --> Errors appear:
   ArgumentException: An item with the same key has already been added. Key: 1665640498 System.Collections.Generic.Dictionary2[TKey,TValue].TryInsert (TKey key, TValue value, System.Collections.Generic.InsertionBehavior behavior) (at <3ead76266f1846f192cd3a42f27e86c3>:0)
   System.Collections.Generic.Dictionary2[TKey,TValue].Add (TKey key, TValue value) (at <3ead76266f1846f192cd3a42f27e86c3>:0) Unity.Netcode.Components.NetworkAnimator.InitializeRPCS_NetworkAnimator () (at <e37cad03ab3f46ef9a53281e8b5a2827>:0)
ArgumentException: An item with the same key has already been added. Key: 1724438000 System.Collections.Generic.Dictionary2[TKey,TValue].TryInsert (TKey key, TValue value, System.Collections.Generic.InsertionBehavior behavior) (at <3ead76266f1846f192cd3a42f27e86c3>:0)
   System.Collections.Generic.Dictionary2[TKey,TValue].Add (TKey key, TValue value) (at <3ead76266f1846f192cd3a42f27e86c3>:0) Unity.Netcode.Components.NetworkTransform.InitializeRPCS_NetworkTransform () (at <e37cad03ab3f46ef9a53281e8b5a2827>:0)

[josephan]

I'm also experiencing this error.

[broding]

Experiencing the same problem in Unity 2021.3.12f1 and can confirm its only present when having checked Enter Play Mode Options.

[NoelStephensUnity]

The issue with disabling domain reload is that NGO requires post processing in order to generate internal changes.
If you are making any script changes you will need to keep domain reloading enabled.
If all you are doing is asset placement/world geometry related work then you can disable domain reloading.

[Xajaxaja]

I understand that, but it has worked for all previous versions of NGO, why would it stop working with this version?

Also even though the error is there, the game works perfectly fine, RPCs work etc. Basically the error doesn't stop the code from working, so it seems like an issue that could be handled. Even if there might be special cases where it would not work.

Also enter play mode is such an improvement to workflow that if you need to enable domain reload to play test, it's almost a deal-breaker by itself.

It should at least be investigated to see if there are any workarounds.

[NoelStephensUnity]

I think I see where we could avoid this issue.
Since the domain is not getting reloaded the RPC dictionary is not being cleared on the codegen/ILPP side of things.
This does seem to be a potential regression bug and will investigate the more recent updates to the RPC table generation.