[BUG] nameof does not work on functions

[Thesola10]

Describe the bug
In Amber, the nameof builtin keyword returns the compiled name of a variable in-scope. Unfortunately, it doesn't currently work for functions.

To Reproduce
Compile the following:

fun a() {
    echo "Trapped"
}

trust $trap {nameof a} SIGTERM SIGKILL SIGINT SIGABRT$

This will fail with the message: Variable 'a' not found

Expected behavior
The script compiles successfully, and {nameof a} is replaced with the compiled name of the function (something akin to a__1_v0)

Additional context
As shown in the example above, the ability to use nameof on functions is necessary to use them in traps, for instance.