fix: TypeError with hasOwnProperty in deepFindPathToProperty (#234)

* chore: add failing test for response having null value

* Revert "fix: add `null` check in `deepFindPathToProperty` function (#137)"

This reverts commit cfda527.

* fix: hasOwnProperty error in deepFindPathToProperty

Author: kachick

src/object-helpers.ts

@@ -1,33 +1,35 @@
 import { MissingPageInfo } from "./errors.js";
 
-const isObject = (value: any) =>
+type unknownObject = Record<string | number | symbol, unknown>;
+
+const isObject = (value: unknown): value is unknownObject =>
   Object.prototype.toString.call(value) === "[object Object]";
 
 function findPaginatedResourcePath(responseData: any): string[] {
-  const paginatedResourcePath: string[] | null = deepFindPathToProperty(
+  const paginatedResourcePath = deepFindPathToProperty(
     responseData,
     "pageInfo",
   );
-  if (paginatedResourcePath === null || paginatedResourcePath.length === 0) {
+  if (paginatedResourcePath.length === 0) {
     throw new MissingPageInfo(responseData);
   }
   return paginatedResourcePath;
 }
 
 const deepFindPathToProperty = (
-  object: any,
+  object: unknownObject,
   searchProp: string,
   path: string[] = [],
 ): string[] => {
   for (const key of Object.keys(object)) {
     const currentPath = [...path, key];
     const currentValue = object[key];
 
-    if (currentValue.hasOwnProperty(searchProp)) {
-      return currentPath;
-    }
-
     if (isObject(currentValue)) {
+      if (currentValue.hasOwnProperty(searchProp)) {
+        return currentPath;
+      }
+
       const result = deepFindPathToProperty(
         currentValue,
         searchProp,

test/extract-page-infos.test.ts

@@ -1,3 +1,4 @@
+import { MissingPageInfo } from "../src/errors.js";
 import { extractPageInfos } from "../src/extract-page-info.js";
 import type { PageInfoContext } from "../src/page-info.js";
 
@@ -63,4 +64,10 @@ describe("extractPageInfos()", (): void => {
       pathInQuery: ["data", "repository", "issues"],
     });
   });
+
+  it("throws a MissingPageInfo error if the response has unexpected structure", async (): Promise<void> => {
+    expect(() => extractPageInfos({ unknown1: null, unknown2: 42 })).toThrow(
+      MissingPageInfo,
+    );
+  });
 });