Support Typescript Assertion Functions

[cowwoc]

Per https://www.typescriptlang.org/docs/handbook/release-notes/typescript-3-7.html#assertion-functions the following Typescript code is valid:

/**
 * Throws an <code>Error</code> if <code>condition</code> is false.
 *
 * @param {boolean} condition a condition
 * @param {Error} [error = Error] the type of error to throw
 * @param {string} message the error message to use on failure
 * @throws {Error} if <code>condition</code> is false
 */
static assert(condition: boolean, error: (message?: string) => Error = Error, message?: string):
	asserts condition
{
	// Will be stripped out using uglify.js option "pure_funcs"
	if (!condition)
		throw error(message);
}

However, when I run jsdoc against using better-docs/typescript plugin I get:

ERROR: Unable to parse a tag's type expression for source file C:\Users\Gili\Documents\requirements.js\target\jsdoc-workaround\internal\Objects.ts in line 429 with tag title "return" and text "{asserts condition}": Invalid type expression "asserts condition": Expected "|" but "c" found.

As a workaround, I now replace all instances of "asserts condition" with "void" before running jsdoc. This made the error disappear.