Hi I have a problem with code compilation, tell me how to fix it

a simple mod in which an item becomes like a backpack. there is an item and a Gui for it but for some reason the compilation fails. here is the error code

> Configure project :
Fabric Loom: 1.4.6
> Task :compileJava FAILED
D:\moi_____mod\src\main\java\net\mcreator\backpack\init\BackpackModItems.java:20: error: cannot find symbol BACK = register("back", new BackItem());
^
symbol: class BackItem
location: class BackpackModItems
1 error
FAILURE: Build failed with an exception.
* What went wrong:
Execution failed for task ':compileJava'.
> Compilation failed; see the compiler error output for details.
* Try:
> Run with --info option to get more log output.
> Run with --scan to get full insights.
BUILD FAILED in 2s
1 actionable task: 1 executed