Don't display line numbers if buffer width is 0 and softwrap is on

If softwrap is enabled, the line numbers displayed in the ruler depend
on the heights of the displayed softwrapped lines, which depend on the
width of the displayed buffer. If this width is 0 (e.g. after resizing
buffer pane to a very small width), there is no displayed text at all,
so line numbers don't make sense. So don't display line numbers in this
case.

internal/display/bufwindow.go

@@ -337,7 +337,7 @@ func (w *BufWindow) drawLineNum(lineNumStyle tcell.Style, softwrapped bool, vloc
 	}
 	// Write the actual line number
 	for i := 0; i < len(lineNum) && vloc.X < w.gutterOffset; i++ {
-		if softwrapped {
+		if softwrapped || (w.bufWidth == 0 && w.Buf.Settings["softwrap"] == true) {
 			screen.SetContent(w.X+vloc.X, w.Y+vloc.Y, ' ', nil, lineNumStyle)
 		} else {
 			screen.SetContent(w.X+vloc.X, w.Y+vloc.Y, lineNum[i], nil, lineNumStyle)