[Fabric] [1.19] SyncedProperty<T> on a ScreenHandler doesn't work at all

[Jankoy]

I'm trying to write a handled screen for a block entity, and using regular owo-lib networking works fine, but if I try to use synced properties like in the example mod, it just doesn't work. It doesn't sync at all. I don't know if I'm missing something or if it just doesn't work. If I'm missing something it would be really helpful to add exact steps to the documentation.

[Jankoy]

Turns out I do get a weird error with the ScreenHander packet sending. Sometimes I get an error for accessing index zero of an array with size zero in the mixin.

[22:46:39] [Netty Local Client IO #0/ERROR] (ClientPlayNetworkAddon for Player418) Encountered exception while handling in channel with name "owo:local_packet"
 java.lang.IndexOutOfBoundsException: Index 0 out of bounds for length 0
	at jdk.internal.util.Preconditions.outOfBounds(Preconditions.java:64) ~[?:?]
	at jdk.internal.util.Preconditions.outOfBoundsCheckIndex(Preconditions.java:70) ~[?:?]
	at jdk.internal.util.Preconditions.checkIndex(Preconditions.java:266) ~[?:?]
	at java.util.Objects.checkIndex(Objects.java:361) ~[?:?]
	at java.util.ArrayList.get(ArrayList.java:427) ~[?:?]
	at net.minecraft.screen.ScreenHandler.owo$handlePacket(ScreenHandler.java:1747) ~[minecraft-merged-f2f8a096fc-1.19.2-net.fabricmc.yarn.1_19_2.1.19.2+build.28-v2.jar:?]
	at io.wispforest.owo.client.screens.ScreenInternals$Client.lambda$init$1(ScreenInternals.java:50) ~[owo-lib-0.9.3+1.19.jar:?]
	at net.fabricmc.fabric.impl.networking.client.ClientPlayNetworkAddon.receive(ClientPlayNetworkAddon.java:106) ~[fabric-networking-api-v1-1.2.12+def3f86d90.jar:?]
	at net.fabricmc.fabric.impl.networking.client.ClientPlayNetworkAddon.receive(ClientPlayNetworkAddon.java:42) ~[fabric-networking-api-v1-1.2.12+def3f86d90.jar:?]
	at net.fabricmc.fabric.impl.networking.AbstractChanneledNetworkAddon.handle(AbstractChanneledNetworkAddon.java:101) [fabric-networking-api-v1-1.2.12+def3f86d90.jar:?]
	at net.fabricmc.fabric.impl.networking.client.ClientPlayNetworkAddon.handle(ClientPlayNetworkAddon.java:98) [fabric-networking-api-v1-1.2.12+def3f86d90.jar:?]
	at net.minecraft.client.network.ClientPlayNetworkHandler.handler$zjd000$fabric-networking-api-v1$handleCustomPayload(ClientPlayNetworkHandler.java:2533) [minecraft-merged-f2f8a096fc-1.19.2-net.fabricmc.yarn.1_19_2.1.19.2+build.28-v2.jar:?]
	at net.minecraft.client.network.ClientPlayNetworkHandler.onCustomPayload(ClientPlayNetworkHandler.java) [minecraft-merged-f2f8a096fc-1.19.2-net.fabricmc.yarn.1_19_2.1.19.2+build.28-v2.jar:?]
	at net.minecraft.network.packet.s2c.play.CustomPayloadS2CPacket.apply(CustomPayloadS2CPacket.java:56) [minecraft-merged-f2f8a096fc-1.19.2-net.fabricmc.yarn.1_19_2.1.19.2+build.28-v2.jar:?]
	at net.minecraft.network.packet.s2c.play.CustomPayloadS2CPacket.apply(CustomPayloadS2CPacket.java:32) [minecraft-merged-f2f8a096fc-1.19.2-net.fabricmc.yarn.1_19_2.1.19.2+build.28-v2.jar:?]
	at net.minecraft.network.ClientConnection.handlePacket(ClientConnection.java:173) [minecraft-merged-f2f8a096fc-1.19.2-net.fabricmc.yarn.1_19_2.1.19.2+build.28-v2.jar:?]
	at net.minecraft.network.ClientConnection.channelRead0(ClientConnection.java:159) [minecraft-merged-f2f8a096fc-1.19.2-net.fabricmc.yarn.1_19_2.1.19.2+build.28-v2.jar:?]
	at net.minecraft.network.ClientConnection.channelRead0(ClientConnection.java:65) [minecraft-merged-f2f8a096fc-1.19.2-net.fabricmc.yarn.1_19_2.1.19.2+build.28-v2.jar:?]
	at io.netty.channel.SimpleChannelInboundHandler.channelRead(SimpleChannelInboundHandler.java:99) [netty-transport-4.1.77.Final.jar:?]
	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379) [netty-transport-4.1.77.Final.jar:?]
	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365) [netty-transport-4.1.77.Final.jar:?]
	at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357) [netty-transport-4.1.77.Final.jar:?]
	at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1410) [netty-transport-4.1.77.Final.jar:?]
	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379) [netty-transport-4.1.77.Final.jar:?]
	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365) [netty-transport-4.1.77.Final.jar:?]
	at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:919) [netty-transport-4.1.77.Final.jar:?]
	at io.netty.channel.local.LocalChannel.readInbound(LocalChannel.java:299) [netty-transport-4.1.77.Final.jar:?]
	at io.netty.channel.local.LocalChannel.finishPeerRead0(LocalChannel.java:445) [netty-transport-4.1.77.Final.jar:?]
	at io.netty.channel.local.LocalChannel.access$400(LocalChannel.java:50) [netty-transport-4.1.77.Final.jar:?]
	at io.netty.channel.local.LocalChannel$5.run(LocalChannel.java:403) [netty-transport-4.1.77.Final.jar:?]
	at io.netty.util.concurrent.AbstractEventExecutor.runTask$$$capture(AbstractEventExecutor.java:174) [netty-common-4.1.77.Final.jar:?]
	at io.netty.util.concurrent.AbstractEventExecutor.runTask(AbstractEventExecutor.java) [netty-common-4.1.77.Final.jar:?]
	at io.netty.channel.DefaultEventLoop.run(DefaultEventLoop.java:54) [netty-transport-4.1.77.Final.jar:?]
	at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:995) [netty-common-4.1.77.Final.jar:?]
	at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74) [netty-common-4.1.77.Final.jar:?]
	at java.lang.Thread.run(Thread.java:840) [?:?]

[gliscowo]

While I won't be able to really provide you with much support in way of fixes to the library (1.19 has long reached end-of-support), I might be able to help you use it.

Could you maybe provide some more context on the surrounding code and your usage of properties? I should point out again (although I do believe this is stated in the docs and thus I assume you know it) that they only sync from server to client, not vice-versa.

Cheers

[Jankoy]

Which docs are you referencing? The only docs I know of don't mention synced properties at all.

[Dragon-Seeker]

I assume they are referring to java docs