gh-153731: Handle NUL and lone surrogate in sqlite3 CLI REPL

[tonghuaroot]

In the python -m sqlite3 REPL, complete_statement() raises ValueError
(embedded NUL) or UnicodeEncodeError (lone surrogate), neither of which is a
sqlite3.Error, so a single such input line crashed the shell. Catch these two
and print an error, keeping the REPL running like the other error paths.

• Issue: sqlite3 command-line interface crashes on a NUL byte or lone surrogate in an input line #153731

[aisk]

UnicodeEncodeError is actually a subclass of ValueError, so catching both is redundant.

But the main question is that ValueError is not narrow, many code paths may raise it. I think it's better to just add a pre-check to see whether \0 is in the input, and then show an error to the user.

We can also use a similar approach to check whether a lone surrogate is in the input, but I'm not an expert on Unicode, and UnicodeEncodeError is a narrow exception, so I think it's okay to keep catching it.

[tonghuaroot]

Done in ab23364: pre-check \0 for the NUL (no longer catching the broad ValueError) and keep catching the narrow UnicodeEncodeError for a lone surrogate.

[aisk]

In this code path, passing an SQL statement on the command line without using the REPL may cause the same error. Maybe we should check it here too.

[tonghuaroot]

Good catch. Done in 49a5763: execute() now applies the same NUL pre-check + narrow UnicodeEncodeError catch, so the direct command-line path is guarded too; added command-line tests.