fix sveltejs#4170: Destructuring undefined property now return 'undef…

…ined'

src/compiler/compile/render_dom/Renderer.ts

@@ -153,7 +153,7 @@ export default class Renderer {
 		const member = this.context_lookup.get(name);
 
 		if (variable && (variable.subscribable && (variable.reassigned || variable.export_name))) {
-			return x`${`$$subscribe_${name}`}($$invalidate(${member.index}, ${value || name}))`;
+			return x`${`$$subscribe_${name}`}($$invalidate({ i: ${member.index}, ret: ${value || name} }))`;
 		}
 
 		if (name[0] === '$' && name[1] !== '$') {
@@ -171,7 +171,7 @@ export default class Renderer {
 		}
 
 		if (value) {
-			return x`$$invalidate(${member.index}, ${value})`;
+			return x`$$invalidate({ i: ${member.index}, ret: ${value} })`;
 		}
 
 		// if this is a reactive declaration, invalidate dependencies recursively
@@ -193,7 +193,7 @@ export default class Renderer {
 		if (!filtered.length) return null;
 
 		return filtered
-			.map(n => x`$$invalidate(${this.context_lookup.get(n).index}, ${n})`)
+			.map(n => x`$$invalidate({ i: ${this.context_lookup.get(n).index}, ret: ${n} })`)
 			.reduce((lhs, rhs) => x`${lhs}, ${rhs}}`);
 	}
 

src/compiler/compile/render_dom/index.ts

@@ -235,7 +235,7 @@ export default function dom(
 
 			const insert = (reassigned || export_name)
 				? b`${`$$subscribe_${name}`}()`
-				: b`@component_subscribe($$self, ${name}, #value => $$invalidate(${i}, ${value} = #value))`;
+				: b`@component_subscribe($$self, ${name}, #value => $$invalidate({ i: ${i}, ret: ${value} = #value }))`;
 
 			if (component.compile_options.dev) {
 				return b`@validate_store(${name}, '${name}'); ${insert}`;
@@ -308,7 +308,7 @@ export default function dom(
 		})
 		.map(({ name }) => b`
 			${component.compile_options.dev && b`@validate_store(${name.slice(1)}, '${name.slice(1)}');`}
-			@component_subscribe($$self, ${name.slice(1)}, $$value => $$invalidate(${renderer.context_lookup.get(name).index}, ${name} = $$value));
+			@component_subscribe($$self, ${name.slice(1)}, $$value => $$invalidate({ i: ${renderer.context_lookup.get(name).index}, ret: ${name} = $$value }));
 		`);
 
 	const resubscribable_reactive_store_unsubscribers = reactive_stores
@@ -359,7 +359,7 @@ export default function dom(
 				const subscribe = `$$subscribe_${name}`;
 				const i = renderer.context_lookup.get($name).index;
 
-				return b`let ${$name}, ${unsubscribe} = @noop, ${subscribe} = () => (${unsubscribe}(), ${unsubscribe} = @subscribe(${name}, $$value => $$invalidate(${i}, ${$name} = $$value)), ${name})`;
+				return b`let ${$name}, ${unsubscribe} = @noop, ${subscribe} = () => (${unsubscribe}(), ${unsubscribe} = @subscribe(${name}, $$value => $$invalidate({ i: ${i}, ret: ${$name} = $$value })), ${name})`;
 			}
 
 			return b`let ${$name};`;

src/compiler/compile/render_dom/invalidate.ts

@@ -62,7 +62,11 @@ export function invalidate(renderer: Renderer, scope: Scope, node: Node, names:
 			let invalidate = is_store_value
 				? x`@set_store_value(${head.name.slice(1)}, ${node}, ${extra_args})`
 				: !main_execution_context
-					? x`$$invalidate(${renderer.context_lookup.get(head.name).index}, ${node}, ${extra_args})`
+					? x`$$invalidate({
+							i: ${renderer.context_lookup.get(head.name).index},
+							ret: ${node},
+							value: ${extra_args[0]}
+						}, ${extra_args.slice(1)})`
 					: node;
 
 			if (head.subscribable && head.reassigned) {

src/runtime/internal/Component.ts

@@ -127,12 +127,29 @@ export function init(component, options, instance, create_fragment, not_equal, p
 	let ready = false;
 
 	$$.ctx = instance
-		? instance(component, prop_values, (i, ret, value = ret) => {
-			if ($$.ctx && not_equal($$.ctx[i], $$.ctx[i] = value)) {
-				if ($$.bound[i]) $$.bound[i](value);
-				if (ready) make_dirty(component, i);
+		? instance(component, prop_values, (args) => {
+			let { i, ret, value } = args;
+			const isValuePassed = !!Object.keys(args).find(e => e === 'value');
+
+			const assign = () => {
+				if (not_equal($$.ctx[i], ($$.ctx[i] = value))) {
+					if ($$.bound[i]) $$.bound[i](value);
+					if (ready) make_dirty(component, i);
+				}
+			};
+
+			if ($$.ctx) {
+				if (!isValuePassed && typeof $$.ctx[i] === 'undefined') {
+					assign();
+					return ret;
+				}
+
+				value = isValuePassed ? value : (value || ret);
+				assign();
 			}
+
 			return ret;
+
 		})
 		: [];