sin function is used as id

[MuhammadSawalhy]

Describtion

When automult = true and singleCharName = true, if you try to parse an expression in which you used builtin functions as identifers, you will get an AST of "automult"s.

Reproduce

sin^2x
sin + x

Actual behaviour

It is parsed as s*i*n^(2x) and s*i*n + x respectively.

Expected behaviour

I expect a syntax error to be thrown:

the function "sin", it used with no arguments! can not use the function a variable!