Add more null checks

Signed-off-by: shedaniel <daniel@shedaniel.me>

gradle.properties

@@ -1,5 +1,5 @@
 org.gradle.jvmargs=-Xmx3G
-mod_version=4.6.2
+mod_version=4.6.3
 supported_version=1.16.x
 minecraft_version=1.16.1
 yarn_version=1.16.1+build.4+legacy.20w09a+build.8

src/main/java/me/shedaniel/rei/impl/ClientHelperImpl.java

@@ -156,6 +156,8 @@ public class ClientHelperImpl implements ClientHelper, ClientModInitializer {
     public boolean tryCheatingEntry(EntryStack entry) {
         if (entry.getType() != EntryStack.Type.ITEM)
             return false;
+        if (MinecraftClient.getInstance().player == null) return false;
+        if (MinecraftClient.getInstance().player.inventory == null) return false;
         ItemStack cheatedStack = entry.getItemStack().copy();
         if (ConfigObject.getInstance().isGrabbingItems() && MinecraftClient.getInstance().currentScreen instanceof CreativeInventoryScreen) {
             PlayerInventory inventory = MinecraftClient.getInstance().player.inventory;