fix options.parent.markdown bug

debug/simplemde.js

@@ -16875,7 +16875,7 @@ var SimpleMDE = function (_Action) {
 		if (!options.previewRender) {
 			// Note: "this" refers to the options object
 			options.previewRender = function (plainText) {
-				return _this.parent.markdown(plainText);
+				return options.parent.markdown(plainText);
 			};
 		}
 

src/js/simplemde.js

@@ -140,7 +140,7 @@ class SimpleMDE extends Action {
 		// Add default preview rendering function
 		if(!options.previewRender) {
 			// Note: "this" refers to the options object
-			options.previewRender = plainText => this.parent.markdown(plainText)
+			options.previewRender = plainText => options.parent.markdown(plainText)
 		}
 
 		// Set default options for parsing config