Fix region overwriting in combine line match

highlighter.go

@@ -7,8 +7,14 @@ import (
 
 func combineLineMatch(src, dst LineMatch) LineMatch {
 	for k, v := range src {
+		if g, ok := dst[k]; ok {
+			if g == "" {
 				dst[k] = v
 			}
+		} else {
+			dst[k] = v
+		}
+	}
 	return dst
 }
 
@@ -123,9 +129,11 @@ func (h *Highlighter) highlightEmptyRegion(start int, canMatchEnd bool, lineNum
 		matches := FindAllIndex(p.regex, line, start == 0, canMatchEnd)
 		for _, m := range matches {
 			highlights[start+m[0]] = p.group
+			if _, ok := highlights[start+m[1]]; !ok {
 				highlights[start+m[1]] = ""
 			}
 		}
+	}
 
 	if canMatchEnd {
 		h.states[lineNum] = nil