fix search text highlight on zero width match

src/textarea.rs

@@ -1008,10 +1008,12 @@ impl<'a> TextArea<'a> {
         #[cfg(feature = "search")]
         if let Some(pat) = &self.search_pat {
             for m in pat.find_iter(line) {
+                if m.start() != m.end() {
                     boundaries.push((Boundary::Search(self.search_style), m.start()));
                     boundaries.push((Boundary::End, m.end()));
                 }
             }
+        }
 
         if boundaries.is_empty() {
             spans.push(Span::raw(self.replace_tabs(line)));