test: ✅ Fixed URL parsing to fix failing test

Modified URL parsing so that endSrmp and endBack
are returned as undefined rather than null when no
end milepost is specified to match previous behavior.
The previous version actually worked in the app but
was causing the unit test to fail.

src/elc/url.ts

@@ -288,7 +288,7 @@ export function getElcParamsFromUrl(
 
 	const { srmp: endSrmp, back: endBack } = emp
 		? parseSrmp(emp)
-		: { srmp: null, back: null };
+		: { srmp: undefined, back: undefined };
 	const output = {
 		Route: route,
 		Srmp: srmp,