Index: node_modules/immer/src/plugins/mapset.ts
===================================================================
--- node_modules/immer/src/plugins/mapset.ts	(revision a762898ecd37a452c782821d4c2c4955c6ed2521)
+++ node_modules/immer/src/plugins/mapset.ts	(revision a762898ecd37a452c782821d4c2c4955c6ed2521)
@@ -0,0 +1,304 @@
+// types only!
+import {
+	ImmerState,
+	AnyMap,
+	AnySet,
+	MapState,
+	SetState,
+	DRAFT_STATE,
+	getCurrentScope,
+	latest,
+	isDraftable,
+	createProxy,
+	loadPlugin,
+	markChanged,
+	die,
+	ArchType,
+	each
+} from "../internal"
+
+export function enableMapSet() {
+	class DraftMap extends Map {
+		[DRAFT_STATE]: MapState
+
+		constructor(target: AnyMap, parent?: ImmerState) {
+			super()
+			this[DRAFT_STATE] = {
+				type_: ArchType.Map,
+				parent_: parent,
+				scope_: parent ? parent.scope_ : getCurrentScope()!,
+				modified_: false,
+				finalized_: false,
+				copy_: undefined,
+				assigned_: undefined,
+				base_: target,
+				draft_: this as any,
+				isManual_: false,
+				revoked_: false
+			}
+		}
+
+		get size(): number {
+			return latest(this[DRAFT_STATE]).size
+		}
+
+		has(key: any): boolean {
+			return latest(this[DRAFT_STATE]).has(key)
+		}
+
+		set(key: any, value: any) {
+			const state: MapState = this[DRAFT_STATE]
+			assertUnrevoked(state)
+			if (!latest(state).has(key) || latest(state).get(key) !== value) {
+				prepareMapCopy(state)
+				markChanged(state)
+				state.assigned_!.set(key, true)
+				state.copy_!.set(key, value)
+				state.assigned_!.set(key, true)
+			}
+			return this
+		}
+
+		delete(key: any): boolean {
+			if (!this.has(key)) {
+				return false
+			}
+
+			const state: MapState = this[DRAFT_STATE]
+			assertUnrevoked(state)
+			prepareMapCopy(state)
+			markChanged(state)
+			if (state.base_.has(key)) {
+				state.assigned_!.set(key, false)
+			} else {
+				state.assigned_!.delete(key)
+			}
+			state.copy_!.delete(key)
+			return true
+		}
+
+		clear() {
+			const state: MapState = this[DRAFT_STATE]
+			assertUnrevoked(state)
+			if (latest(state).size) {
+				prepareMapCopy(state)
+				markChanged(state)
+				state.assigned_ = new Map()
+				each(state.base_, key => {
+					state.assigned_!.set(key, false)
+				})
+				state.copy_!.clear()
+			}
+		}
+
+		forEach(cb: (value: any, key: any, self: any) => void, thisArg?: any) {
+			const state: MapState = this[DRAFT_STATE]
+			latest(state).forEach((_value: any, key: any, _map: any) => {
+				cb.call(thisArg, this.get(key), key, this)
+			})
+		}
+
+		get(key: any): any {
+			const state: MapState = this[DRAFT_STATE]
+			assertUnrevoked(state)
+			const value = latest(state).get(key)
+			if (state.finalized_ || !isDraftable(value)) {
+				return value
+			}
+			if (value !== state.base_.get(key)) {
+				return value // either already drafted or reassigned
+			}
+			// despite what it looks, this creates a draft only once, see above condition
+			const draft = createProxy(value, state)
+			prepareMapCopy(state)
+			state.copy_!.set(key, draft)
+			return draft
+		}
+
+		keys(): IterableIterator<any> {
+			return latest(this[DRAFT_STATE]).keys()
+		}
+
+		values(): IterableIterator<any> {
+			const iterator = this.keys()
+			return {
+				[Symbol.iterator]: () => this.values(),
+				next: () => {
+					const r = iterator.next()
+					/* istanbul ignore next */
+					if (r.done) return r
+					const value = this.get(r.value)
+					return {
+						done: false,
+						value
+					}
+				}
+			} as any
+		}
+
+		entries(): IterableIterator<[any, any]> {
+			const iterator = this.keys()
+			return {
+				[Symbol.iterator]: () => this.entries(),
+				next: () => {
+					const r = iterator.next()
+					/* istanbul ignore next */
+					if (r.done) return r
+					const value = this.get(r.value)
+					return {
+						done: false,
+						value: [r.value, value]
+					}
+				}
+			} as any
+		}
+
+		[Symbol.iterator]() {
+			return this.entries()
+		}
+	}
+
+	function proxyMap_<T extends AnyMap>(target: T, parent?: ImmerState): T {
+		// @ts-ignore
+		return new DraftMap(target, parent)
+	}
+
+	function prepareMapCopy(state: MapState) {
+		if (!state.copy_) {
+			state.assigned_ = new Map()
+			state.copy_ = new Map(state.base_)
+		}
+	}
+
+	class DraftSet extends Set {
+		[DRAFT_STATE]: SetState
+		constructor(target: AnySet, parent?: ImmerState) {
+			super()
+			this[DRAFT_STATE] = {
+				type_: ArchType.Set,
+				parent_: parent,
+				scope_: parent ? parent.scope_ : getCurrentScope()!,
+				modified_: false,
+				finalized_: false,
+				copy_: undefined,
+				base_: target,
+				draft_: this,
+				drafts_: new Map(),
+				revoked_: false,
+				isManual_: false
+			}
+		}
+
+		get size(): number {
+			return latest(this[DRAFT_STATE]).size
+		}
+
+		has(value: any): boolean {
+			const state: SetState = this[DRAFT_STATE]
+			assertUnrevoked(state)
+			// bit of trickery here, to be able to recognize both the value, and the draft of its value
+			if (!state.copy_) {
+				return state.base_.has(value)
+			}
+			if (state.copy_.has(value)) return true
+			if (state.drafts_.has(value) && state.copy_.has(state.drafts_.get(value)))
+				return true
+			return false
+		}
+
+		add(value: any): any {
+			const state: SetState = this[DRAFT_STATE]
+			assertUnrevoked(state)
+			if (!this.has(value)) {
+				prepareSetCopy(state)
+				markChanged(state)
+				state.copy_!.add(value)
+			}
+			return this
+		}
+
+		delete(value: any): any {
+			if (!this.has(value)) {
+				return false
+			}
+
+			const state: SetState = this[DRAFT_STATE]
+			assertUnrevoked(state)
+			prepareSetCopy(state)
+			markChanged(state)
+			return (
+				state.copy_!.delete(value) ||
+				(state.drafts_.has(value)
+					? state.copy_!.delete(state.drafts_.get(value))
+					: /* istanbul ignore next */ false)
+			)
+		}
+
+		clear() {
+			const state: SetState = this[DRAFT_STATE]
+			assertUnrevoked(state)
+			if (latest(state).size) {
+				prepareSetCopy(state)
+				markChanged(state)
+				state.copy_!.clear()
+			}
+		}
+
+		values(): IterableIterator<any> {
+			const state: SetState = this[DRAFT_STATE]
+			assertUnrevoked(state)
+			prepareSetCopy(state)
+			return state.copy_!.values()
+		}
+
+		entries(): IterableIterator<[any, any]> {
+			const state: SetState = this[DRAFT_STATE]
+			assertUnrevoked(state)
+			prepareSetCopy(state)
+			return state.copy_!.entries()
+		}
+
+		keys(): IterableIterator<any> {
+			return this.values()
+		}
+
+		[Symbol.iterator]() {
+			return this.values()
+		}
+
+		forEach(cb: any, thisArg?: any) {
+			const iterator = this.values()
+			let result = iterator.next()
+			while (!result.done) {
+				cb.call(thisArg, result.value, result.value, this)
+				result = iterator.next()
+			}
+		}
+	}
+	function proxySet_<T extends AnySet>(target: T, parent?: ImmerState): T {
+		// @ts-ignore
+		return new DraftSet(target, parent)
+	}
+
+	function prepareSetCopy(state: SetState) {
+		if (!state.copy_) {
+			// create drafts for all entries to preserve insertion order
+			state.copy_ = new Set()
+			state.base_.forEach(value => {
+				if (isDraftable(value)) {
+					const draft = createProxy(value, state)
+					state.drafts_.set(value, draft)
+					state.copy_!.add(draft)
+				} else {
+					state.copy_!.add(value)
+				}
+			})
+		}
+	}
+
+	function assertUnrevoked(state: any /*ES5State | MapState | SetState*/) {
+		if (state.revoked_) die(3, JSON.stringify(latest(state)))
+	}
+
+	loadPlugin("MapSet", {proxyMap_, proxySet_})
+}