Print a warning when plugin rank cannot be changed

src/debug.js

@@ -31,14 +31,23 @@ const ytDebugger = new Debug.Debugger('YouTube', {
     high_precision: true,
 });
 
-function _debug(msg, debuggerName)
+function _logStructured(debuggerName, msg, level)
+{
+    GLib.log_structured(
+        debuggerName, level, {
+            MESSAGE: msg,
+            SYSLOG_IDENTIFIER: debuggerName.toLowerCase()
+    });
+}
+
+function _debug(debuggerName, msg)
 {
     if(msg.message) {
-        GLib.log_structured(
-            debuggerName, GLib.LogLevelFlags.LEVEL_CRITICAL, {
-                MESSAGE: msg.message,
-                SYSLOG_IDENTIFIER: debuggerName.toLowerCase()
-        });
+        _logStructured(
+            debuggerName,
+            msg.message,
+            GLib.LogLevelFlags.LEVEL_CRITICAL
+        );
 
         return;
     }
@@ -55,10 +64,15 @@ function _debug(msg, debuggerName)
 
 function debug(msg)
 {
-    _debug(msg, 'Clapper');
+    _debug('Clapper', msg);
 }
 
 function ytDebug(msg)
 {
-    _debug(msg, 'YouTube');
+    _debug('YouTube', msg);
+}
+
+function warn(msg)
+{
+    _logStructured('Clapper', msg, GLib.LogLevelFlags.LEVEL_WARNING);
 }

src/player.js

@@ -6,7 +6,7 @@ const YouTube = imports.src.youtube;
 const { PlaylistWidget } = imports.src.playlist;
 const { WebApp } = imports.src.webApp;
 
-const { debug } = Debug;
+const { debug, warn } = Debug;
 const { settings } = Misc;
 
 let WebServer;
@@ -119,8 +119,10 @@ class ClapperPlayer extends GstClapper.Clapper
     {
         const gstRegistry = Gst.Registry.get();
         const feature = gstRegistry.lookup_feature(name);
-        if(!feature)
-            return debug(`plugin unavailable: ${name}`);
+        if(!feature) {
+            warn(`cannot change rank of unavailable plugin: ${name}`);
+            return;
+        }
 
         const oldRank = feature.get_rank();
         if(rank === oldRank)