micro: Don't forward nil events into the sub event handler

[JoeKar]

Currently the Redraw() performed by the UpdateDiff() will bring the raw pane into trouble. According to #2991 (comment) it's possible to have the redraw event without a parallel tcell event and this can lead to event pointer de-references in the sub event handler.

Fixes #2991

[dmaluka]

One more reason to merge this PR: #3011

[octoshrimpy]

is there any reason this is still being held up?

[dmaluka]

@zyedidia ping.

[xxuejie]

Hey so I'm bisecting a regression to this PR. It seems that the change here is breaking existing behavior when an interactive shell is used. To reproduce it:

• Install this plugin: https://github.com/samdmarshall/micro-fzf-plugin
• Execute fzf command
• Even though the plugin is configured so we don't wait for terminal output, micro will always prompt with the message Press enter to continue

So maybe there is a corner case that is not handled here? Or am I doing things the wrong way?

Thanks!

[dmaluka]

Yeah, this is a regression, thanks for reporting. We missed that since commit b68461c the terminal code has been (slightly hackily) relying on nil events as notifications to close the terminal:

b68461c#diff-f4c689c96c13af20e2e9fc3cfdb39b4549de701266748f0acaac5c5b4ce92fd6R113

so now micro doesn't close the terminal automatically, so you see this Press enter to close instead.

I think we can fix it in a better way. I'll try to fix it shortly.

[dmaluka]

Fixed by #3386

[xxuejie]

Thanks! I can confirm that #3386 indeed fixes the issue.