fix handling of plain MFM tag

packages/client/src/components/mfm.ts

@@ -51,6 +51,10 @@ export default defineComponent({
 
 		const genEl = (ast: mfm.MfmNode[]) => ast.map((token): VNode | VNode[] => {
 			switch (token.type) {
+				case 'plain':
+					// for some reason `<plain>` is a token which just wraps a single text node
+					token = token.children[0];
+					// fallthrough
 				case 'text': {
 					const text = token.props.text.replace(/(\r\n|\n|\r)/g, '\n');