Unnecessary restrictions or misleading error messages due to relying on truthiness #274

The reliance on JavaScript's truthiness leads to many methods failing on valid, if atypical, input. For example, many (probably almost all) places where the code has !options.length leads to unnecessary failure, e.g. string, buffer, wrapped, and more. Of course, this applies to options.lengthInBytes and likely other fields.

As a concrete example, this program fails unnecessarily and misleadingly with "Error: One of length, zeroTerminated, or greedy must be defined for string."

const Parser = require("binary-parser").Parser;
const example = new Parser().string("foo", {length: 0});
const buf = Buffer.from("deadbeef", "hex");
console.log(example.parse(buf));

If you really do want to disallow 0 in these cases (and "" potentially in some others, etc.), then these cases should be checked for explicitly and an error message about 0 being an invalid value produced. Generally, I recommend against ever relying on JavaScript's truthiness. Something like typescript-eslint's strict-boolean-expressions can help with this.