Added a clearer error message in the log of the output

Author: mesonepigreco

Modules/Cluster.py

@@ -622,12 +622,16 @@ def prepare_input_file(self, structures, calc, labels):
 
                 list_of_inputs.append(input_file)     
                 list_of_outputs.append(output_file)
-            except:
+            except Exception as e: 
                 MSG = '''
 Error while writing input file {}.
+
+Error message:
 '''.format(label)
+                MSG += str(e)
                 print(MSG)
 
+
             # Release the lock on the threads
             self.lock.release()