An error occurred while trying to compile a function with a return value of VOID in debug mode.

[chen4s666]

Describe the bug
An error occurred while trying to compile a function with a return value of VOID in debug mode.

To Reproduce
The test uses the ST code as follows.
FUNCTION abc : VOID END_FUNCTION

Add the -g argument and compile it.
The error information is as follows.

thread 'main' panicked at src\codegen\debug.rs:522:18: Type should exist at this stage note: run with RUST_BACKTRACE=1 environment variable to display a backtrace

This was supposed to be introduced in #1103