typechecking

With Closure Compiler v20210106 and the following flags:

--language_in=ECMASCRIPT_NEXT
--compilation_level ADVANCED
--js tmp/wrap.js 

This works fine:

/**
 * @param {string} str
 * @param {string} [prefix=aa]
 * @param {string} [suffix=bb]
 */
function wrap1(str, prefix="aa", suffix="bb") {
  return prefix + str + suffix;
}

window.wrap1 = wrap

While working on #300, I noticed that (after the fix is applied) the error messages display end-of-file as being on column 1 of line 1. This is probably caused by EOF token being created without relevant lexer context.

I took a quick look, and I think this is the relevant code:

https://github.com/SebastianMestre/Jasper/blob/03a95e0ca841791ce9ccbe073a2e79649799a421/src/lexer.cpp#L383-L391