Class ReportableError

source code

              object --+            
                       |            
exceptions.BaseException --+        
                           |        
        exceptions.Exception --+    
                               |    
                           Error --+
                                   |
                                  ReportableError

is raised when something decides it can come up with an error message that should be presented to the user as-is.

UIs should, consequently, just dump the payload and not try adornments. The content should be treated as a unicode string.