fix(index): change .options to a private field

Author: zhouhongxuan

src/index.ts

@@ -26,8 +26,6 @@ export default class Highlighter extends EventEmitter {
 
     static isHighlightWrapNode = isHighlightWrapNode;
 
-    options: HighlighterOptions;
-
     hooks: HookMap;
 
     painter: Painter;
@@ -36,6 +34,8 @@ export default class Highlighter extends EventEmitter {
 
     private _hoverId: string;
 
+    private options: HighlighterOptions;
+
     private readonly event = getInteraction();
 
     constructor(options?: HighlighterOptions) {