fix: #791 return 'nothing' should produce undefined patch

__tests__/patch.js

@@ -5,7 +5,8 @@ import produce, {
 	produceWithPatches,
 	enableAllPlugins,
 	isDraft,
-	immerable
+	immerable,
+	nothing
 } from "../src/immer"
 
 enableAllPlugins()
@@ -1277,3 +1278,10 @@ test("#648 assigning object to itself should not change patches", () => {
 		}
 	])
 })
+
+test("#791 patch for  nothing is stored as undefined", () => {
+	const [newState, patches] = produceWithPatches({abc: 123}, draft => nothing)
+	expect(patches).toEqual([{op: "replace", path: [], value: undefined}])
+
+	expect(applyPatches({}, patches)).toEqual(undefined)
+})

src/plugins/patches.ts

@@ -20,7 +20,8 @@ import {
 	Archtype,
 	die,
 	isDraft,
-	isDraftable
+	isDraftable,
+	NOTHING
 } from "../internal"
 
 export function enablePatches() {
@@ -190,7 +191,7 @@ export function enablePatches() {
 		patches.push({
 			op: REPLACE,
 			path: [],
-			value: replacement
+			value: replacement === NOTHING ? undefined : replacement
 		})
 		inversePatches.push({
 			op: REPLACE,