fix(router): type cast correctly for IE 11 bug breaking URL Unificati…

…on when comparing objects (#30464)

PR #30393 corrected behavior where Object.keys sometimes returns an `undefined` value. However, the types didn't reflect this in the code. That fix actually missed one value that could return `undefined`. This PR corrects this by casting the types to what they can be in IE 11. This ensures the code behaves as it should when this edge case comes up.

PR Close #30464

packages/router/src/utils/collection.ts

@@ -21,10 +21,13 @@ export function shallowEqualArrays(a: any[], b: any[]): boolean {
 }
 
 export function shallowEqual(a: {[x: string]: any}, b: {[x: string]: any}): boolean {
-  const k1 = Object.keys(a);
-  const k2 = Object.keys(b);
-  // IE 11 sometimes returns an `undefined` value here. This guard is for IE 11 only.
-  if (!(k1 || k2) || k1.length != k2.length) {
+  // Casting Object.keys return values to include `undefined` as there are some cases
+  // in IE 11 where this can happen. Cannot provide a test because the behavior only
+  // exists in certain circumstances in IE 11, therefore doing this cast ensures the
+  // logic is correct for when this edge case is hit.
+  const k1 = Object.keys(a) as string[] | undefined;
+  const k2 = Object.keys(b) as string[] | undefined;
+  if (!k1 || !k2 || k1.length != k2.length) {
     return false;
   }
   let key: string;