micro crashes when the raw buffer contains more than 1000 lines

[MSDcrafter]

Description of the problem or steps to reproduce

micro crashes with an nil pointer dereference, when the raw buffer is opened and filled with more than 1000 lines of events.

max@X2:~/tmp/micro$ ./micro 
Micro encountered an error: runtime.errorString runtime error: invalid memory address or nil pointer dereference
runtime/panic.go:220 (0x44ccb6)
runtime/panic.go:219 (0x44cc86)
github.com/zyedidia/micro/v2/internal/action/rawpane.go:37 (0x8a5c93)
github.com/zyedidia/micro/v2/internal/action/tab.go:269 (0x8a744e)
github.com/zyedidia/micro/v2/internal/action/tab.go:139 (0x8a69d6)
github.com/zyedidia/micro/v2/cmd/micro/micro.go:476 (0x8d5fdc)
github.com/zyedidia/micro/v2/cmd/micro/micro.go:394 (0x8d596e)
runtime/proc.go:250 (0x439152)
runtime/asm_amd64.s:1571 (0x467de1)
 
If you can reproduce this error, please report it at https://github.com/zyedidia/micro/issues
max@X2:~/tmp/micro$ 

Steps to reproduce:

1. open micro
2. open the raw pane
3. cause more than 1000 events (scrolling is the easiest method)

Specifications

As far as i can see, this is caused by DoEvent() in cmd/micro/micro.go:476:1 passing along a nil event. And there seems to be a line that checks for this situation at cmd/micro/micro.go:472:1.
However, that line is commented out and since i do now know why it is commented out, i did not want to submit a commit that uncomments it and potentially breaks something.

Commit hash: d8e9d61
OS: Linux Mint 21.1
Terminal: x-terminal-emulator

[JoeKar]

I can confirm that it crashes with 1000th entry, but currently I'm unsure if it's really caused by micro or reveals something in tcell. Because it looks like the nil event is coming from tcell.

Edit 1:
tcell doesn't create that nil event. Drawing is the cause and the event is still nil, since tcell doesn't trigger that processing cycle.

Edit 2:
buffer.go#L1192 -> bufwindow.go#L385 -> BOOM!

Suggestion:
Since the Redraw() is explicit wanted/intended we should really check event against nil before touching everything starting from micro.go#L452 in the DoEvent(), because everything is related to an event fired by tcell and received by micro, even the EventError check prevents the crash at this position, it will fail afterwards.