I have managed to isolate the bug and create a new workspace to demonstrate it. I have attached the exported workspace zip to this report. I also left some comments inside the procedure where said bug takes place in order to give some context.
Here is the console output:
Executing Gradle task: build Build info: MCreator 2020.2.13719, 1.14.4, 64-bit, 16030 MB, Linux, JVM 1.8.0_232, JAVA_HOME: /home/awesome/Desktop/MCreator20202/jdk/jre > Configure project : New Dep: net.minecraftforge:forge:1.14.4-28.2.3_mapped_snapshot_20190719-1.14.3 > Task :compileJava FAILED /home/awesome/MCreatorWorkspaces/bugdemo/src/main/java/net/mcreator/bugdemo/procedures/HereisthebugProcedure.java:51: error: local variables referenced from an inner class must be final or effectively final /home/awesome/MCreatorWorkspaces/bugdemo/src/main/java/net/mcreator/bugdemo/procedures/HereisthebugProcedure.java:51: error: local variables referenced from an inner class must be final or effectively final ItemStack retval = ((new ItemStack((world.getBlockState(new BlockPos((int) (verible), (int) y, (int) z))).getBlock()))).copy(); ^ 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 --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights. * Get more help at https://help.gradle.org Deprecated Gradle features were used in this build, making it incompatible with Gradle 5.0. Use '--warning-mode all' to show the individual deprecation warnings. See https://docs.gradle.org/4.9/userguide/command_line_interface.html#sec:command_line_warnings BUILD FAILED in 2s 1 actionable task: 1 executed BUILD FAILED Task completed in 4390 milliseconds
Also sorry about my username, i was in a bad mood when i created this account 2 years ago.