[cmdlog] sheets created with no keypresses show errors

[midichef]

Small description
clicking on dir_hidden in the DirSheet guide raises an exception

Actual result with screenshot

File "/home/midichef/.local/lib/python3.10/site-packages/visidata/statusbar.py", line 56, in sheetlist
if len(vs.shortcut) == 1:
TypeError: object of type 'NoneType' has no len()

Steps to reproduce with sample data and a .vd
vd ., navigate to filename column to bring the DirSheet guide up, click on dir_hidden

Additional context
visidata 3.1dev

It looks like vs.shortcut is None because some code for shortcut() is obsolete, where it checks cmdlog.rows[0].keystrokes:

visidata/visidata/cmdlog.py

Line 415 in aa9d261

return self.cmdlog_sheet.rows[0].keystrokes

[midichef]

Okay I've got a clearer idea of exactly when this happens. It's when you create a sheet without using keystrokes. Like a command started by exec-command, or a help menubar entry, or clicking a statusbar link. The sheet has to have precious == False, like a HelpSheet or OptionsSheet. So. running exec-longname and then choosing help-commands.

visidata/visidata/cmdlog.py

Line 412 in c702c35

return str(vd.allSheets.index(self)+1)

Because the sheet isn't precious, it can't be found in vd.allSheets, so the command log is searched for keystrokes. But there are no keystrokes because the action that triggered the command wasn't a keypress.

[midichef]

As a secondary issue, I wonder if

visidata/visidata/cmdlog.py

Line 417 in c702c35

return self.cmdlog_sheet.rows[0].keystrokes

has a remaining problem, when it uses rows[0]. It assumes the first row of the command log is the one that created the sheet. But they're usually set-options commands. (This same assumption caused a problem with undo in #2244.) It seems like that may cause an error.

I haven't yet found a case it does. But before I dig deeper, what is this shortcut code for? What's an example where a keystroke from the command log can be thought of as a shortcut?

[saulpw]

What is this shortcut code for? What's an example where a keystroke from the command log can be thought of as a shortcut?

The shortcut shown on the status bar before the sheetname: 1›sample. For regular sheets, it's assigned; the intention is that if you opened a non-precious sheet, the "shortcut" would be the key you used to open it, like C for the columns sheet or O for the options sheet. But this usage was disabled (when Shift+C just did not look right and I wasn't sure about it anyway), so these days the shortcut is only meaningful for precious sheets.

Thanks for looking into all this, by the way. I know this code can get pretty convoluted over time.