fix: prevent undefined value when remount keyed input element with spread props (#7699)

Fixes: #7578

When remounting a keyed input element (e.g. because the element order has changed) with spread properties, the input value gets undefined. This has happened because data_value is updated before remounting and it won't contain a value for input-value (because the value hasn't changed). When calling mount() an undefined value was assigned because of a missing check.

src/compiler/compile/render_dom/wrappers/Element/index.ts

@@ -886,7 +886,9 @@ export default class ElementWrapper extends Wrapper {
 			const type = this.node.get_static_attribute_value('type');
 			if (type === null || type === '' || type === 'text' || type === 'email' || type === 'password') {
 				block.chunks.mount.push(b`
+					if ('value' in ${data}) {
 						${this.var}.value = ${data}.value;
+					}
 				`);
 				block.chunks.update.push(b`
 					if ('value' in ${data}) {

test/runtime/samples/spread-element-input-each-block-keyed/_config.js

@@ -0,0 +1,11 @@
+export default {
+	test({ assert, component, target }) {
+		const [input1, input2] = target.querySelectorAll('input');
+		assert.equal(input1.value, 'value1');
+		assert.equal(input2.value, 'value2');
+
+		component.items = component.items.reverse();
+		assert.equal(input1.value, 'value1');
+		assert.equal(input2.value, 'value2');
+	}
+};

test/runtime/samples/spread-element-input-each-block-keyed/main.svelte

@@ -0,0 +1,7 @@
+<script>
+	export let items = ['value1', 'value2'];
+</script>
+
+{#each items as item (item)}
+	<input value={item} {...{}} />
+{/each}