Add SyntaxError check for pdb's command display

[gaogaotiantian]

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.

Linked PRs

• gh-103023: Add SyntaxError check in pdb's display command #103024

[ambv]

That's a reasonable improvement, thanks for taking the time to report and implement this!