Ensure get_bytecode_instructions doesn't crash and improve error messages

[CocytusDEDI]

While I think the whole spelltranslator.rs needs to be inspected, In particular, the if statement testing needs to be looked over.

[CocytusDEDI]

Error messages could include line numbers as well

[CocytusDEDI]

Progress on avoiding crashes was made, but better error messages still need to be added. Maybe even dynamic error messages.

[AndycptSher]

crashes in spelltranslator still possible by express panic! macros in:

• get_precdence (line 117)
• get_associative_direction (line 131)
• collect_parameters (line 654)