Add SyntaxError check for pdb's command display #103023
Description
Feature or enhancement
Check SyntaxError when doing display in pdb.
Pitch
display adds an expression to watch list. However, if there's a syntax error, then the command is meaningless. Currently, display still adds this invalid expression into the watch list, which does not make sense in almost all cases. Adding a syntax error check could prevent the users from accidentally adding wrong expressions then having to remove it with undisplay.