add braces around instrumented block-less if statements etc

src/compile/render-dom/index.ts

@@ -163,7 +163,7 @@ export default function dom(
 				}
 			},
 
-			leave(node) {
+			leave(node, parent) {
 				if (map.has(node)) {
 					scope = scope.parent;
 				}
@@ -211,6 +211,9 @@ export default function dom(
 							} else {
 								code.prependRight(node.start, `${insert}; `);
 							}
+						} else if (parent && /(If|For(In|Of)?|While)Statement/.test(parent.type) && node.type !== 'BlockStatement') {
+							code.prependRight(node.start, '{ ');
+							code.appendLeft(node.end, `${code.original[node.end - 1] === ';' ? '' : ';'} ${insert}; }`);
 						} else {
 							code.appendLeft(node.end, `${code.original[node.end - 1] === ';' ? '' : ';'} ${insert};`);
 						}