fix: throw proper immer error when applyPatches path traverses null

__tests__/patch.js

@@ -1596,3 +1596,12 @@ describe("RTK-5159: Patch path truncation bug", () => {
 		expect(patches[0].path).toEqual(["queries", "queryKey", "data", "items", 1])
 	})
 })
+test("applyPatches throws proper immer error when intermediate path value is null", () => {
+	// isObjectish(null) === true (typeof null === "object"), so the null check
+	// inside applyPatches_ was missing; navigating into null threw a native
+	// TypeError instead of immer's own "path doesn't resolve" error.
+	const isProd = process.env.NODE_ENV === "production"
+	expect(() => {
+		applyPatches({a: null}, [{op: "add", path: ["a", "b"], value: 1}])
+	}).toThrow(isProd ? "18" : "Cannot apply patch, path doesn't resolve: a/b")
+})

src/plugins/patches.ts

@@ -345,7 +345,8 @@ export function enablePatches() {
 					die(errorOffset + 3)
 				if (isFunction(base) && p === PROTOTYPE) die(errorOffset + 3)
 				base = get(base, p)
-				if (!isObjectish(base)) die(errorOffset + 2, path.join("/"))
+				if (base === null || !isObjectish(base))
+					die(errorOffset + 2, path.join("/"))
 			}
 
 			const type = getArchtype(base)