The command has indeed failed with message:
Argument X was previously inferred to be in scope function_scope but is here
used in the empty scope stack. Scope function_scope will be used at parsing
time unless you override it by annotating the argument with an explicit scope
of choice. [inconsistent-scopes,syntax]
The command has indeed failed with message:
Simple notations don't support only printing
The command has indeed failed with message:
The reference nonexisting was not found in the current environment.
The command has indeed failed with message:
Notation scope for argument X can be specified only once.
pp I
     : True /\ True
The command has indeed failed with message:
Illegal application (Non-functional construction): 
The expression "I" of type "True" cannot be applied to the term
 "I" : "True"
File "stdin", line 21, characters 0-50:
Warning: This notation will not be used for printing as it is bound to a
single variable. [notation-bound-to-variable,parsing]