Implement null check for the 'findPaginatedResourcePath' function

Previously the `deepFindPathToProperty` function would occasionally fail with `TypeError: Cannot read properties of null (reading 'hasOwnProperty')`. This change fixes that by adding a null check to the `findPaginatedResourcePath` function.

Resolves octokit#58

src/object-helpers.ts

@@ -4,11 +4,11 @@ const isObject = (value: any) =>
   Object.prototype.toString.call(value) === "[object Object]";
 
 function findPaginatedResourcePath(responseData: any): string[] {
-  const paginatedResourcePath = deepFindPathToProperty(
+  const paginatedResourcePath: string[] | null = deepFindPathToProperty(
     responseData,
     "pageInfo",
   );
-  if (paginatedResourcePath.length === 0) {
+  if (paginatedResourcePath === null || paginatedResourcePath.length === 0) {
     throw new MissingPageInfo(responseData);
   }
   return paginatedResourcePath;