Change skin-caching feature to be fail-safe (fixes #561)

src/main/java/com/replaymod/replay/mixin/Mixin_FixNPCSkinCaching.java

@@ -2,6 +2,7 @@ package com.replaymod.replay.mixin;
 
 import net.minecraft.client.MinecraftClient;
 import net.minecraft.client.network.AbstractClientPlayerEntity;
+import net.minecraft.client.network.OtherClientPlayerEntity;
 import net.minecraft.client.network.PlayerListEntry;
 import org.spongepowered.asm.mixin.Mixin;
 import org.spongepowered.asm.mixin.Shadow;
@@ -24,8 +25,19 @@ public abstract class Mixin_FixNPCSkinCaching {
         // intended ones. To fix that, we make this caching-glitch which servers have come to rely on an actual feature
         // by just fetching the cache in the constructor which arguably is what MC should have done to begin with,
         // especially because the spawn packet handling code already requires the entry to be present).
-        if (MinecraftClient.getInstance().getNetworkHandler() != null) { // will be null if this is the client player
+
+        // To reduce the chance of incompatibility with custom player entities, we only do this for the vanilla MP one.
+        //noinspection ConstantConditions
+        if (!(((Object) this) instanceof OtherClientPlayerEntity)) return;
+
+        // To get the player list entry, we need to be connected (we usually are, but better be safe than sorry)
+        if (MinecraftClient.getInstance().getNetworkHandler() == null) return;
+
+        // And we catch any exceptions, so if there is still something, it's hopefully not fatal
+        try {
             this.getPlayerListEntry();
+        } catch (Exception e) {
+            e.printStackTrace();
         }
     }
 }