fix: validate stream_url and clear stale session on error

Co-authored-by: Cursor <cursoragent@cursor.com>

src/lib/stores/videoSession.svelte.ts

@@ -38,19 +38,7 @@ export function setMetadata(meta: VideoMetadata) {
   session.thumbnailSpritesheets = [];
 }
 
-export function setError(msg: string) {
-  session.status = 'error';
-  session.error = msg;
-}
-
-export function setResolving() {
-  session.status = 'resolving';
-  session.error = null;
-}
-
-export function reset() {
-  session.status = 'idle';
-  session.error = null;
+function clearMediaFields() {
   session.url = '';
   session.title = '';
   session.duration = 0;
@@ -65,3 +53,21 @@ export function reset() {
   session.waveformPeaks = [];
   session.thumbnailSpritesheets = [];
 }
+
+export function setError(msg: string) {
+  reset();
+  session.status = 'error';
+  session.error = msg;
+}
+
+export function setResolving() {
+  clearMediaFields();
+  session.status = 'resolving';
+  session.error = null;
+}
+
+export function reset() {
+  clearMediaFields();
+  session.status = 'idle';
+  session.error = null;
+}