Disallow newline directly following `//`
> **<sup>Lexer</sup>**\
> LINE_COMMENT :\
-> &nbsp;&nbsp; &nbsp;&nbsp; `//` (~\[`/` `!`] | `//`) ~`\n`<sup>\*</sup>\
+> &nbsp;&nbsp; &nbsp;&nbsp; `//` (~\[`/` `!` `\n`] | `//`) ~`\n`<sup>\*</sup>\
> &nbsp;&nbsp; | `//`
>
> BLOCK_COMMENT :\
