Better error when escaping keyword as variable name

[ArtemkaKun]

error(E0001): unexpected input character U+0040 `@`, bytes: [64], len: 1
 --> wrapper.sp:11894:40:41
       |
 11894 | return C.tsMeshIndices_getTypeName_MIT(@type)
       |                                        ^ 

After Discord discussion - Spawn wouldn't support keywords escape, so there should be a better error like "seems you are trying to escape keyword to use it as variable name, but Spawn doesn't support this"