prevent transitions during HMR update

Author: Rich-Harris

packages/svelte/src/internal/client/dev/hmr.js

@@ -1,5 +1,6 @@
-import { block, branch, pause_effect } from '../reactivity/effects.js';
+import { block, branch, destroy_effect } from '../reactivity/effects.js';
 import { set, source } from '../reactivity/sources.js';
+import { set_should_intro } from '../render.js';
 import { get } from '../runtime.js';
 
 /**
@@ -27,11 +28,13 @@ export function hmr(data, component) {
 				if (effect) {
 					// @ts-ignore
 					for (var k in instance) delete instance[k];
-					pause_effect(effect);
+					destroy_effect(effect);
 				}
 
 				effect = branch(() => {
+					set_should_intro(false);
 					Object.assign(instance, component(anchor, props));
+					set_should_intro(true);
 				});
 			});