Fix highlighters being applied to empty display buffers

In some cases such as with folding we can end-up with regions
not having any atoms to highlight which can trigger a crash as
we assume display buffers not to be empty

Fixes #4926

1 files changed, 3 insertions, 0 deletions

diff --git a/src/highlighters.cc b/src/highlighters.cc
index d2daa085..ee772469 100644
--- a/src/highlighters.cc
+++ b/src/highlighters.cc
@@ -1840,6 +1840,9 @@ struct ForwardHighlighterApplier
                 cur_atom = cur_line->begin();
         }
 
+        if (region_lines.empty())
+            return;
+
         region_display.compute_range();
         highlighter.highlight(context, region_display, {begin, end});