fix: ensure type widening for bind:group

#2316

Author: dummdidumm

packages/svelte2tsx/src/htmlxtojsx_v2/nodes/Binding.ts

@@ -59,9 +59,13 @@ export function handleBinding(
 ): void {
     // bind group on input
     if (element instanceof Element && attr.name == 'group' && parent.name == 'input') {
+        // add reassignment to force TS to widen the type of the declaration (in case it's never reassigned anywhere else)
+        const expressionStr = str.original.substring(
+            attr.expression.start,
+            getEnd(attr.expression)
+        );
         element.appendToStartEnd([
-            rangeWithTrailingPropertyAccess(str.original, attr.expression),
-            ';'
+            surroundWithIgnoreComments(`() => ${expressionStr} = __sveltets_2_any(null);`)
         ]);
         return;
     }

packages/svelte2tsx/test/htmlx2jsx/samples/binding-group-bare/expectedv2.js

@@ -1,6 +1,6 @@
 ///<reference types="svelte" />
 ;function render() {
-async () => { { svelteHTML.createElement("input", {      "id":`dom-input`,"type":`radio`,"value":`dom`,});$compile_options.generate;}};
+async () => { { svelteHTML.createElement("input", {     "id":`dom-input`,"type":`radio`,"value":`dom`,});/*Ωignore_startΩ*/() => $compile_options.generate = __sveltets_2_any(null);/*Ωignore_endΩ*/}};
 return { props: /** @type {Record<string, never>} */ ({}), slots: {}, events: {} }}
 
 export default class Input__SvelteComponent_ extends __sveltets_2_createSvelte2TsxComponent(__sveltets_2_partial(__sveltets_2_with_any_event(render()))) {