fix server-side crashes

src/main/java/net/fretux/skillengine/api/SkillEngineAPI.java

@@ -3,7 +3,6 @@ package net.fretux.skillengine.api;
 import net.fretux.skillengine.SkillEngine;
 import net.fretux.skillengine.capability.PlayerSkillData;
 import net.fretux.skillengine.capability.SkillEngineCapabilities;
-import net.fretux.skillengine.client.SkilltreeClientState;
 import net.fretux.skillengine.skilltree.AbilityNode;
 import net.fretux.skillengine.skilltree.AbilityNodeRegistry;
 import net.fretux.skillengine.skilltree.SkillLogic;
@@ -11,6 +10,8 @@ import net.fretux.skillengine.skilltree.SkillNode;
 import net.fretux.skillengine.skilltree.SkillNodeRegistry;
 import net.minecraft.resources.ResourceLocation;
 import net.minecraft.world.entity.player.Player;
+import net.minecraftforge.api.distmarker.Dist;
+import net.minecraftforge.fml.loading.FMLEnvironment;
 
 import java.util.List;
 import java.util.Set;
@@ -130,14 +131,28 @@ public final class SkillEngineAPI {
     }
 
     public static boolean clientHasSkill(ResourceLocation id) {
-        return SkilltreeClientState.isUnlocked(id);
+        return FMLEnvironment.dist == Dist.CLIENT && ClientAccess.clientHasSkill(id);
     }
 
     public static int clientGetAbilitySlot(ResourceLocation id) {
-        return SkilltreeClientState.getSlotOfAbility(id);
+        return FMLEnvironment.dist == Dist.CLIENT ? ClientAccess.clientGetAbilitySlot(id) : -1;
     }
 
     public static ResourceLocation[] clientGetAbilitySlots() {
-        return SkilltreeClientState.getAbilitySlots();
+        return FMLEnvironment.dist == Dist.CLIENT ? ClientAccess.clientGetAbilitySlots() : new ResourceLocation[3];
     }
-}
+
+    private static final class ClientAccess {
+        private static boolean clientHasSkill(ResourceLocation id) {
+            return net.fretux.skillengine.client.SkilltreeClientState.isUnlocked(id);
+        }
+
+        private static int clientGetAbilitySlot(ResourceLocation id) {
+            return net.fretux.skillengine.client.SkilltreeClientState.getSlotOfAbility(id);
+        }
+
+        private static ResourceLocation[] clientGetAbilitySlots() {
+            return net.fretux.skillengine.client.SkilltreeClientState.getAbilitySlots();
+        }
+    }
+}

src/main/java/net/fretux/skillengine/client/AbilityKeybindHandler.java

@@ -4,13 +4,14 @@ import com.mojang.blaze3d.platform.InputConstants;
 import net.fretux.skillengine.network.PacketHandler;
 import net.fretux.skillengine.network.ServerboundActivateAbilityPacket;
 import net.minecraft.client.KeyMapping;
+import net.minecraftforge.api.distmarker.Dist;
 import net.minecraftforge.client.event.InputEvent;
 import net.minecraftforge.client.settings.KeyConflictContext;
 import net.minecraftforge.eventbus.api.SubscribeEvent;
 import net.minecraftforge.fml.common.Mod;
 import org.lwjgl.glfw.GLFW;
 
-@Mod.EventBusSubscriber
+@Mod.EventBusSubscriber(modid = net.fretux.skillengine.SkillEngine.MODID, value = Dist.CLIENT)
 public class AbilityKeybindHandler {
 
     public static final KeyMapping ABILITY_1 = new KeyMapping(

src/main/java/net/fretux/skillengine/network/ClientboundNodeUnlockedPacket.java

@@ -3,8 +3,9 @@ package net.fretux.skillengine.network;
 import net.fretux.skillengine.skilltree.AbilityNodeRegistry;
 import net.minecraft.network.FriendlyByteBuf;
 import net.minecraft.resources.ResourceLocation;
+import net.minecraftforge.api.distmarker.Dist;
+import net.minecraftforge.fml.DistExecutor;
 import net.minecraftforge.network.NetworkEvent;
-import net.fretux.skillengine.client.SkilltreeClientState;
 
 import java.util.function.Supplier;
 
@@ -30,13 +31,20 @@ public class ClientboundNodeUnlockedPacket {
 
     public static void handle(ClientboundNodeUnlockedPacket msg, Supplier<NetworkEvent.Context> ctx) {
         ctx.get().enqueueWork(() -> {
-            if (AbilityNodeRegistry.get(msg.id) != null)
+            DistExecutor.unsafeRunWhenOn(Dist.CLIENT, () -> () -> ClientHandler.handle(msg));
-                SkilltreeClientState.unlockAbility(msg.id);
-            else
-                SkilltreeClientState.unlockNode(msg.id);
-            SkilltreeClientState.setCurrentSkillPoints(msg.newSkillPoints);
         });
         ctx.get().setPacketHandled(true);
     }
+
+    private static final class ClientHandler {
+        private static void handle(ClientboundNodeUnlockedPacket msg) {
+            if (AbilityNodeRegistry.get(msg.id) != null) {
+                net.fretux.skillengine.client.SkilltreeClientState.unlockAbility(msg.id);
+            } else {
+                net.fretux.skillengine.client.SkilltreeClientState.unlockNode(msg.id);
+            }
+            net.fretux.skillengine.client.SkilltreeClientState.setCurrentSkillPoints(msg.newSkillPoints);
+        }
+    }
 }
 

src/main/java/net/fretux/skillengine/network/ClientboundSyncCooldownPacket.java

@@ -1,7 +1,8 @@
 package net.fretux.skillengine.network;
 
-import net.fretux.skillengine.client.SkilltreeClientState;
 import net.minecraft.network.FriendlyByteBuf;
+import net.minecraftforge.api.distmarker.Dist;
+import net.minecraftforge.fml.DistExecutor;
 import net.minecraftforge.network.NetworkEvent;
 
 import java.util.function.Supplier;
@@ -26,7 +27,13 @@ public class ClientboundSyncCooldownPacket {
     }
 
     public static void handle(ClientboundSyncCooldownPacket msg, Supplier<NetworkEvent.Context> ctx) {
-        ctx.get().enqueueWork(() -> SkilltreeClientState.updateCooldown(msg.slot, msg.cooldown));
+        ctx.get().enqueueWork(() -> DistExecutor.unsafeRunWhenOn(Dist.CLIENT, () -> () -> ClientHandler.handle(msg)));
         ctx.get().setPacketHandled(true);
     }
+
+    private static final class ClientHandler {
+        private static void handle(ClientboundSyncCooldownPacket msg) {
+            net.fretux.skillengine.client.SkilltreeClientState.updateCooldown(msg.slot, msg.cooldown);
+        }
+    }
 }

src/main/java/net/fretux/skillengine/network/ClientboundSyncSkillsPacket.java

@@ -1,8 +1,9 @@
 package net.fretux.skillengine.network;
 
-import net.fretux.skillengine.client.SkilltreeClientState;
 import net.minecraft.network.FriendlyByteBuf;
 import net.minecraft.resources.ResourceLocation;
+import net.minecraftforge.api.distmarker.Dist;
+import net.minecraftforge.fml.DistExecutor;
 import net.minecraftforge.network.NetworkEvent;
 
 import java.util.HashSet;
@@ -63,11 +64,17 @@ public class ClientboundSyncSkillsPacket {
 
     public static void handle(ClientboundSyncSkillsPacket msg, Supplier<NetworkEvent.Context> ctx) {
         ctx.get().enqueueWork(() -> {
-            SkilltreeClientState.setUnlocked(msg.unlocked);
+            DistExecutor.unsafeRunWhenOn(Dist.CLIENT, () -> () -> ClientHandler.handle(msg));
-            SkilltreeClientState.setUnlockedAbilities(msg.unlockedAbilities);
-            SkilltreeClientState.setCurrentSkillPoints(msg.skillPoints);
-            SkilltreeClientState.setAbilitySlots(msg.abilitySlots);
         });
         ctx.get().setPacketHandled(true);
     }
-}
+
+    private static final class ClientHandler {
+        private static void handle(ClientboundSyncSkillsPacket msg) {
+            net.fretux.skillengine.client.SkilltreeClientState.setUnlocked(msg.unlocked);
+            net.fretux.skillengine.client.SkilltreeClientState.setUnlockedAbilities(msg.unlockedAbilities);
+            net.fretux.skillengine.client.SkilltreeClientState.setCurrentSkillPoints(msg.skillPoints);
+            net.fretux.skillengine.client.SkilltreeClientState.setAbilitySlots(msg.abilitySlots);
+        }
+    }
+}