NXT: function return type is disregarded in show text block

[boonto]

Describe the bug

• When using a function with a return value in a "show text" block the type of the function is disregarded.
• That leads to "TextOut" being generated for all types, which will not compile.

To Reproduce Steps to reproduce the behavior:

1. Create a function with a number return value
2. Connect it to a show text block
3. Try to compile the program
4. See error

Expected behavior

• The program compiles or the blocks are not allowed to be connected to the show text block.

Additional context

• Here is a test file with all return functions which are possible to connect to the show text block.