CharacterPointer elements[13] :=    {"I",  "IV", "V",
                                         "IX", "X",  "XL",
                                         "L",  "XC", "C",
                                         "CD", "D",  "CM",
                                         "M"};

Running the tests...
All the tests passed in 4 milliseconds.
Reading the file "debug.aec"...
All characters read in 0 milliseconds.
Tokenizing the program...
Finished tokenizing the program in 0 milliseconds.
I have made a forum thread about how to speed up the tokenizer,
in case you are interested:
https://www.forum.hr/showthread.php?t=1243509
Parsing the program...
Finished parsing the program in 0 milliseconds.
Compiling the program...
Line 1, Column 43, Internal compiler error: Compiler got into a forbidden state!
Internal compiler error: Uncaught exception in the compiler: 24InvalidTypenameException: Invalid typename!
If you have time, please report this to me on GitHub as an issue:
https://github.com/FlatAssembler/AECforWebAssembly/issues