Fix bug

src/mfm/html.ts

@@ -92,6 +92,10 @@ const handlers: { [key: string]: (window: any, token: any, mentionedRemoteUsers:
 };
 
 export default (tokens: TextElement[], mentionedRemoteUsers: INote['mentionedRemoteUsers'] = []) => {
+	if (tokens == null) {
+		return null;
+	}
+
 	const { window } = new JSDOM('');
 
 	for (const token of tokens) {

src/mfm/parse/index.ts

@@ -43,8 +43,7 @@ export type TextElement = { type: 'text', content: string }
 export type TextElementProcessor = (text: string, i: number) => TextElement | TextElement[];
 
 export default (source: string): TextElement[] => {
-
-	if (source == '') {
+	if (source == null || source == '') {
 		return null;
 	}