WTH exception handling (#1)

* fix the `wth` exception

* add comment for the wth error

* fix indentation

src/router.js

@@ -172,6 +172,7 @@ export const getWorkingPath = (parentRouterId) => {
 	}
 	const stackEntry = stack[parentRouterId];
 	if (!stackEntry) {
+		// this should not be reached at all
 		throw 'wth';
 	}
 
@@ -239,6 +240,10 @@ const process = (stackObj, directCall) => {
 		reducedPath: previousReducedPath
 	} = stackObj;
 
+	if (!stack[routerId]) {
+		return;
+	}
+
 	const currentPath = getWorkingPath(parentRouterId);
 	let route = null;
 	let targetFunction = null;
@@ -270,10 +275,6 @@ const process = (stackObj, directCall) => {
 		break;
 	}
 
-	if (!stack[routerId]) {
-		return;
-	}
-
 	if (!anyMatched) {
 		route = null;
 		targetFunction = null;