connect: prevent loading a context with no tracks

connect/src/state.rs

@@ -43,8 +43,10 @@ pub enum StateError {
     NoContext(ContextType),
     #[error("could not find track {0:?} in context of {1}")]
     CanNotFindTrackInContext(Option<usize>, usize),
-    #[error("Currently {action} is not allowed because {reason}")]
+    #[error("currently {action} is not allowed because {reason}")]
     CurrentlyDisallowed { action: String, reason: String },
+    #[error("the provided context has no tracks")]
+    ContextHasNoTracks,
 }
 
 impl From<StateError> for Error {

connect/src/state/context.rs

@@ -67,6 +67,14 @@ impl ConnectState {
     pub fn update_context(&mut self, mut context: Context) -> Result<(), Error> {
         debug!("context: {}, {}", context.uri, context.url);
 
+        let page = match context.pages.pop() {
+            None => return Ok(()),
+            Some(page) if page.tracks.is_empty() => {
+                return Err(StateError::ContextHasNoTracks.into())
+            }
+            Some(page) => page,
+        };
+
         if context.restrictions.is_some() {
             self.player.restrictions = context.restrictions.clone();
             self.player.context_restrictions = context.restrictions;
@@ -80,11 +88,6 @@ impl ConnectState {
             self.player.context_metadata.insert(key, value);
         }
 
-        let page = match context.pages.pop() {
-            None => return Ok(()),
-            Some(page) => page,
-        };
-
         debug!(
             "updated context from {} ({} tracks) to {} ({} tracks)",
             self.player.context_uri,