fix: handle falsy srcset values (#8901)

fixes #8899

.changeset/early-lizards-decide.md

@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: handle falsy srcset values

packages/svelte/src/runtime/internal/utils.js

@@ -90,12 +90,12 @@ function split_srcset(srcset) {
 
 /**
  * @param {HTMLSourceElement | HTMLImageElement} element_srcset
- * @param {string} srcset
+ * @param {string | undefined | null} srcset
  * @returns {boolean}
  */
 export function srcset_url_equal(element_srcset, srcset) {
 	const element_urls = split_srcset(element_srcset.srcset);
-	const urls = split_srcset(srcset);
+	const urls = split_srcset(srcset || '');
 
 	return (
 		urls.length === element_urls.length &&

packages/svelte/test/utils/utils.test.js

@@ -162,6 +162,7 @@ describe('utils', () => {
 		it('should return false if urls are different', () => {
 			assert.notOk(srcset_url_equal(create_element('a 1x'), 'b 1x'));
 			assert.notOk(srcset_url_equal(create_element('a 2x'), 'a 1x'));
+			assert.notOk(srcset_url_equal(create_element('a 2x'), null));
 		});
 	});
 });