old_contents: 
  
  import sys
  
  import bpy
  from bpy.props import StringProperty
  
  
  class ExportLog(object):
      """ Class which tracks warnings and errors during export """
  
      WARNING = "Warning"
      ERROR = "Error"
  
      MESSAGE_SEPERATOR = "\n"
      SEVERITY_DIVIDER = "|#|"
  
      EXPORTED_MESSAGE_QUEUE = []
  
      def __init__(self):
          self._message_queue = []
  
      def info(self, *args):
          """ Adds a new info, this will not be logged but just printed to stdout """
          print("Info:", *args)
  
      def warning(self, *args):
          """ Adds a new warning to the log """
          self._add_entry(self.WARNING, *args)
  
      def error(self, *args):
          """ Adds a new error to the log """
          self._add_entry(self.ERROR, *args)
  
      def _add_entry(self, severity, *args):
          """ Internal method to append a new entry to the message queue """
          content = ' '.join([str(i) for i in args])
          self._message_queue.append((severity, content))
          print(severity + ":", content, file=sys.stderr)
  
      def report(self):
          """ Shows a dialog with all warnings and errors, but only in case
          there were some """
          
          if self._message_queue:
              ExportLog.EXPORTED_MESSAGE_QUEUE = self._message_queue
              bpy.ops.pbe_export.status()
  
  class OperatorExportStatus(bpy.types.Operator):
      bl_idname = "pbe_export.status"
      bl_label = "Export Status"
   
      def execute(self, context):
          wm = context.window_manager
          return wm.invoke_popup(self, width=800, height=400)
   
      def draw(self, context):
          self.layout.row().label("Export status:")
          self.layout.row()
          for severity, message in ExportLog.EXPORTED_MESSAGE_QUEUE:
              row = self.layout.row()
              message = message.replace("\n", "")
              row.label(message, icon="CANCEL" if severity == ExportLog.ERROR else "ERROR")
  
          self.layout.row()
  
  def register():
      bpy.utils.register_class(OperatorExportStatus)
      bpy.utils.register_class(OperatorExportStatusOk)
  
  
  def unregister():
      bpy.utils.unregister_class(OperatorExportStatus)
      bpy.utils.unregister_class(OperatorExportStatusOk)
  
new_contents: 
  
  import sys
  
  import bpy
  from bpy.props import StringProperty
  
  
  class ExportLog(object):
      """ Class which tracks warnings and errors during export """
  
      WARNING = "Warning"
      ERROR = "Error"
  
      MESSAGE_SEPERATOR = "\n"
      SEVERITY_DIVIDER = "|#|"
  
      EXPORTED_MESSAGE_QUEUE = []
  
      def __init__(self):
          self._message_queue = []
  
      def info(self, *args):
          """ Adds a new info, this will not be logged but just printed to stdout """
          print("Info:", *args)
  
      def warning(self, *args):
          """ Adds a new warning to the log """
          self._add_entry(self.WARNING, *args)
  
      def error(self, *args):
          """ Adds a new error to the log """
          self._add_entry(self.ERROR, *args)
  
      def _add_entry(self, severity, *args):
          """ Internal method to append a new entry to the message queue """
          content = ' '.join([str(i) for i in args])
          self._message_queue.append((severity, content))
          print(severity + ":", content, file=sys.stderr)
  
      def report(self):
          """ Shows a dialog with all warnings and errors, but only in case
          there were some """
          
          if self._message_queue:
              ExportLog.EXPORTED_MESSAGE_QUEUE = self._message_queue
              bpy.ops.pbe_export.status()
  
  class OperatorExportStatus(bpy.types.Operator):
      bl_idname = "pbe_export.status"
      bl_label = "Export Status"
   
      def execute(self, context):
          wm = context.window_manager
          return wm.invoke_popup(self, width=800, height=400)
   
      def draw(self, context):
          self.layout.row().label("Export status:")
          self.layout.row()
          for severity, message in ExportLog.EXPORTED_MESSAGE_QUEUE:
              row = self.layout.row()
              message = message.replace("\n", "")
              row.label(message, icon="CANCEL" if severity == ExportLog.ERROR else "ERROR")
  
          self.layout.row()
  
  def register():
      bpy.utils.register_class(OperatorExportStatus)
      #bpy.utils.register_class(OperatorExportStatusOk)
  
  
  def unregister():
      bpy.utils.unregister_class(OperatorExportStatus)
      #bpy.utils.unregister_class(OperatorExportStatusOk)
  
subject: Fix error loading plug-in