fix: don't issue a11y warning for video without captions if it has no

Author: Rich-Harris

.changeset/dark-buckets-hang.md

@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: don't issue a11y warning for `<video>` without captions if it has no `src`

packages/svelte/src/compiler/phases/2-analyze/visitors/shared/a11y/index.js

@@ -486,9 +486,17 @@ export function check_element(node, context) {
 		case 'video': {
 			const aria_hidden_attribute = attribute_map.get('aria-hidden');
 			const aria_hidden_exist = aria_hidden_attribute && get_static_value(aria_hidden_attribute);
+
 			if (attribute_map.has('muted') || aria_hidden_exist === 'true' || has_spread) {
 				return;
 			}
+
+			if (!attribute_map.has('src')) {
+				// don't warn about missing captions if `<video>` has no `src` —
+				// could e.g. be playing a MediaStream
+				return;
+			}
+
 			let has_caption = false;
 			const track = /** @type {AST.RegularElement | undefined} */ (
 				node.fragment.nodes.find((i) => i.type === 'RegularElement' && i.name === 'track')