in mpl_client.py: sync_fig_format_rawdata(): add the error message to the output.

                                             add a WARNING in case the Error message
                                                 has a <success Flag> (Status.value == True)

mpl_client.py

@@ -298,9 +298,15 @@ class MplClient():
 
             if isinstance(formated_data, Status):
                 if formated_data.value:
-                    print('This should not happen')
+                    print('WARNING: This should not happen...')
+                    print('Client recieved an Error with success status (True):')
+
                 else:
-                    print('instead of answer a error was received')
+                    print('instead of answer an error was received:')
+
+                # Print error message
+                print(str(formated_data.content))
+                
             datas = (None,)
         else:
             # set the figure data to answerSig.value