[1.12.2] Avoid Error.

TeamOpenIndustry#135
TeamOpenIndustry#136

src/main/java/cam72cam/mod/MinecraftClient.java

@@ -17,15 +17,28 @@ public static boolean isReady() {
     }
 
     private static Player playerCache;
-    /** Hey, it's you! */
+    private static Entity entityCache;
+
+	/** Hey, it's you! */
     public static Player getPlayer() {
         EntityPlayerSP internal = Minecraft.getMinecraft().player;
         if (internal == null) {
             throw new RuntimeException("Called to get the player before minecraft has actually started!");
         }
+        if (entityCache == null) {
+            entityCache = World.get(internal.world).getEntity(internal);
+        }
+		// Cannot join immediately after game startup in multiplayer.
+		// The following fixes avoided the error, but the GUI cannot be displayed in IR when the game is joined immediately after startup. 
+		// It is possible to work around it by re-logging in.
         if (playerCache == null || internal != playerCache.internal) {
-            playerCache = World.get(internal.world).getEntity(internal).asPlayer();
+            if (entityCache == null) {
+                playerCache = new Player(Minecraft.getMinecraft().player);
+            } else {
+                playerCache = World.get(internal.world).getEntity(internal).asPlayer();
+            }
         }
+		// -----
         return playerCache;
     }
 

src/main/java/cam72cam/mod/world/World.java

@@ -451,7 +451,7 @@ public void dropItem(ItemStack stack, Vec3d pos) {
     /** Drop a stack on the ground at pos with velocity */
     public void dropItem(ItemStack stack, Vec3d pos, Vec3d velocity) {
         EntityItem entity = new EntityItem(internal, pos.x, pos.y, pos.z, stack.internal);
-        entity.setVelocity(velocity.x, velocity.y, velocity.z);
+//      entity.setVelocity(velocity.x, velocity.y, velocity.z);
         internal.spawnEntity(entity);
     }