MGRS parsing issue

[avenmia]

Wikipedia gives the following examples for MGRS values:

https://en.wikipedia.org/wiki/Military_Grid_Reference_System

4Q .....................GZD only, precision level 6° × 8° (in most cases)
4QFJ ...................GZD and 100 km Grid Square ID, precision level 100 km
4QFJ 1 6 ...............precision level 10 km
4QFJ 12 67 .............precision level 1 km
4QFJ 123 678 ...........precision level 100 m
4QFJ 1234 6789 .........precision level 10 m
4QFJ 12345 67890 .......precision level 1 m

But parsing fails because the parse function in mgrs.js checks if the first two values are of type number.

geodesy/mgrs.js

Lines 149 to 158 in 8f4ef33

	static parse(mgrsGridRef) {
	if (!mgrsGridRef) throw new Error(`invalid MGRS grid reference ‘${mgrsGridRef}’`);
	// check for military-style grid reference with no separators
	if (!mgrsGridRef.trim().match(/\s/)) {
	if (!Number(mgrsGridRef.slice(0, 2))) throw new Error(`invalid MGRS grid reference ‘${mgrsGridRef}’`);
	let en = mgrsGridRef.trim().slice(5); // get easting/northing following zone/band/100ksq
	en = en.slice(0, en.length/2)+' '+en.slice(-en.length/2); // separate easting/northing
	mgrsGridRef = mgrsGridRef.slice(0, 3)+' '+mgrsGridRef.slice(3, 5)+' '+en; // insert spaces
	}

[chrisveness]

Thank you for raising this issue.

I have corrected the MGRS parsing to accept single-digit zones.