Fix a couple of missing Markers.

ui_swing/src/com/dmdirc/addons/ui_swing/components/LoggingSwingWorker.java

 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import static com.dmdirc.util.LogUtils.APP_ERROR;
+
 /**
  * Logging swing worker.
  *
         } catch (InterruptedException ex) {
             //Ignore
         } catch (ExecutionException ex) {
-            LOG.warn(ex.getMessage(), ex);
+            LOG.warn(APP_ERROR, ex.getMessage(), ex);
         }
     }
 

ui_swing/src/com/dmdirc/addons/ui_swing/components/SupplierLoggingSwingWorker.java

 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import static com.dmdirc.util.LogUtils.USER_ERROR;
+
 /**
  * {@link LoggingSwingWorker} that runs a {@link Supplier}.
  */
         } catch (InterruptedException ex) {
             //Ignore
         } catch (ExecutionException ex) {
-            LOG.warn(ex.getMessage(), ex);
+            LOG.warn(USER_ERROR, ex.getMessage(), ex);
         }
     }
 

ui_swing/src/com/dmdirc/addons/ui_swing/dialogs/prefs/PrefsCategoryLoader.java

 import com.dmdirc.config.prefs.PreferencesCategory;
 import com.dmdirc.config.prefs.PreferencesSetting;
 import com.dmdirc.config.prefs.PreferencesType;
-import com.dmdirc.util.LogUtils;
 
 import java.awt.Component;
 import java.awt.MenuContainer;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import static com.dmdirc.util.LogUtils.USER_ERROR;
+
 /**
  * Loads a preferences panel for a specified preferences category in the background.
  */
         } catch (InterruptedException ex) {
             panel = errorCategory;
         } catch (ExecutionException ex) {
-            LOG.warn(LogUtils.USER_ERROR, "Error loading prefs panel", ex);
+            LOG.warn(USER_ERROR, "Error loading prefs panel", ex);
             panel = errorCategory;
         }
         return panel;