jrnl should display an error message when using `--import` and `--format`

[micahellison]

Diagnostic output

jrnl: v4.2.1
Python: 3.10.12 (main, Feb  4 2025, 14:57:36) [GCC 11.4.0]
OS: Linux 5.15.0-136-generic

Current Behavior

To import a jrnl, you pipe data to a jrnl --import call. However, our documentation incorrectly states that you can specify a --format arg after --import (#1485).

Expected Behavior

Instead of being presented with a list of formats, or being told the selected format is wrong, the user should be told that the --format argument is incompatible with the --import argument.

Repro Steps

$ echo "new entry" | jrnl --import --format whatformats
usage: jrnl [--debug] [--help] [--version] [--list] [--encrypt] [--decrypt] [--import] [--template TEMPLATE] [-on DATE]
            [-today-in-history] [-month DATE] [-day DATE] [-year DATE] [-from DATE] [-to DATE] [-contains TEXT] [-and] [-starred]
            [-tagged] [-n [NUMBER]] [-not [TAG/FLAG]] [--edit] [--delete] [--change-time [DATE]] [--format TYPE] [--tags] [--short]
            [--config-override CONFIG_KV_PAIR CONFIG_KV_PAIR] [--config-file CONFIG_FILE_PATH]
            [...]
jrnl: error: argument --format: invalid choice: 'whatformats' (choose from 'boxed', 'calendar', 'dates', 'fancy', 'heatmap', 'json', 'markdown', 'md', 'pretty', 'short', 'tags', 'text', 'txt', 'xml', 'yaml')

$ echo "new entry" | jrnl --import --format text
┏━ Error ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓
┃  AttributeError                                      ┃
┃  'NoneType' object has no attribute 'import_'        ┃
┃                                                      ┃
┃  This is probably a bug. Please file an issue at:    ┃
┃  https://github.com/jrnl-org/jrnl/issues/new/choose  ┃
┗━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┛

Debug output

n/a

Other Information

It would be good to resolve #1485 in the docs while resolving this issue.