Add better logging for file open and write errors

src/core/songloader.cpp

@@ -281,7 +281,7 @@ SongLoader::Result SongLoader::LoadLocalAsync(const QString &filename) {
   // It's a local file, so check if it looks like a playlist. Read the first few bytes.
   QFile file(filename);
   if (!file.open(QIODevice::ReadOnly)) {
-    errors_ << tr("Could not open file %1").arg(filename);
+    errors_ << tr("Could not open file %1 for reading: %2").arg(filename).arg(file.errorString());
     return Error;
   }
   QByteArray data(file.read(PlaylistParser::kMagicSize));
@@ -312,6 +312,10 @@ SongLoader::Result SongLoader::LoadLocalAsync(const QString &filename) {
       }
       return Success;
     }
+    else {
+      errors_ << tr("Could not open CUE file %1 for reading: %2").arg(matching_cue).arg(cue.errorString());
+      return Error;
+    }
   }
 
   // Assume it's just a normal file
@@ -364,6 +368,9 @@ void SongLoader::LoadPlaylist(ParserBase *parser, const QString &filename) {
     songs_ = parser->Load(&file, filename, QFileInfo(filename).path());
     file.close();
   }
+  else {
+    errors_ << tr("Could not open playlist file %1 for reading: %2").arg(filename).arg(file.errorString());
+  }
 
 }