make pyrepl more robust against crashes

[cfbolz]

Bug report

Bug description:

This issue is motivated by a discussion with @serhiy-storchaka on #122456. Pyrepl/code.InteractiveInterpreter does not handle exceptions at various points, see the linked commend for an example.

Directly after writing this, I also got the following traceback that I now can't reproduce, by pressing ctrl-r then searching for a string, and then pressing ctrl-c at somehow the wrong point:

>>> Traceback (most recent call last):
  File "/home/cfbolz/projects/cpython/Lib/_pyrepl/simple_interact.py", line 147, in run_multiline_interactive_console
    statement = multiline_input(more_lines, ps1, ps2)
  File "/home/cfbolz/projects/cpython/Lib/_pyrepl/readline.py", line 385, in multiline_input
    return reader.readline()
           ~~~~~~~~~~~~~~~^^
  File "/home/cfbolz/projects/cpython/Lib/_pyrepl/reader.py", line 773, in readline
    self.handle1()
    ~~~~~~~~~~~~^^
  File "/home/cfbolz/projects/cpython/Lib/_pyrepl/reader.py", line 730, in handle1
    event = self.console.get_event(block)
  File "/home/cfbolz/projects/cpython/Lib/_pyrepl/unix_console.py", line 391, in get_event
    self.push_char(self.__read(1))
                   ~~~~~~~~~~~^^^
  File "/home/cfbolz/projects/cpython/Lib/_pyrepl/unix_console.py", line 203, in __read
    self.input_buffer = os.read(self.input_fd, 10000)
                        ~~~~~~~^^^^^^^^^^^^^^^^^^^^^^
KeyboardInterrupt

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "<frozen runpy>", line 198, in _run_module_as_main
  File "<frozen runpy>", line 88, in _run_code
  File "/home/cfbolz/projects/cpython/Lib/_pyrepl/__main__.py", line 6, in <module>
    __pyrepl_interactive_console()
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^
  File "/home/cfbolz/projects/cpython/Lib/_pyrepl/main.py", line 59, in interactive_console
    run_multiline_interactive_console(console)
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^
  File "/home/cfbolz/projects/cpython/Lib/_pyrepl/simple_interact.py", line 164, in run_multiline_interactive_console
    r.pop_input_trans()
    ~~~~~~~~~~~~~~~~~^^
  File "/home/cfbolz/projects/cpython/Lib/_pyrepl/reader.py", line 546, in pop_input_trans
    self.input_trans = self.input_trans_stack.pop()
                       ~~~~~~~~~~~~~~~~~~~~~~~~~~^^
IndexError: pop from empty list

This crashed pyrepl. I think it would be better if we printed the exception, but then actually stayed in pyrepl, to make sure we don't lose the repl state which might have been annoying to get to.

Another way to crash pyrepl, but not the classic repl is to close sys.stderr and then raising an exception.

We could make pyrepl less crash-prone that by adding an except BaseException around the pyrepl loop in run_multiline_interactive_console.

Any opinions, @pablogsal, @ambv?

CPython versions tested on:

3.13, CPython main branch

Operating systems tested on:

Linux

[feoh]

Hi! I can't reproduce either your Ctrl-r / ctrl-c use case.

Pyrepl exits with a ValueError I/O operation on closed file, which at least seems like a reasonable response to me?

>> import sys
>>> sys.stderr.close()
>>>
>>>
>>> raise(TypeError)
object address  : 0x101ab4830
object refcount : 3
object type     : 0x100cfded0
object type name: ValueError
object repr     : ValueError('I/O operation on closed file.')
lost sys.stderr

[feoh]

@cfbolz @serhiy-storchaka now as seen above, now that #122456 has been merged this issue no longer occurs so could we possibly close this?