diff --git a/.gitignore b/.gitignore
index df2fc162..7fcf9d28 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,5 @@
 dist
+out
 !docs/dist
 dist-*
 cabal-dev
diff --git a/package.json b/package.json
index 945ae088..4ff5bf04 100644
--- a/package.json
+++ b/package.json
@@ -9,7 +9,8 @@
     "setup": "npm i && npm run bootstrap && cd repl && npm i",
     "repl": "cd repl && npm run dev",
     "osc": "cd packages/osc && npm run server",
-    "build": "cd repl && npm run build",
+    "build": "cd repl && npm run build && cd ../tutorial && npm run build",
+    "preview": "npx serve ./out",
     "jsdoc": "jsdoc packages/ -c jsdoc.config.json",
     "jsdoc-json": "jsdoc packages/ --template ./node_modules/jsdoc-json --destination doc.json -c jsdoc.config.json"
   },
diff --git a/packages/tone/draw.mjs b/packages/tone/draw.mjs
index 4fd3ea9e..d894c547 100644
--- a/packages/tone/draw.mjs
+++ b/packages/tone/draw.mjs
@@ -37,6 +37,7 @@ Pattern.prototype.draw = function (callback, cycleSpan, lookaheadCycles = 1) {
         const end = (currentCycle + lookaheadCycles) * cycleSpan;
         events = this._asNumber(true) // true = silent error
           .query(new State(new TimeSpan(begin, end)))
+          .filter(Boolean)
           .filter((event) => event.part.begin.equals(event.whole.begin));
       }
     }
diff --git a/repl/vite.config.js b/repl/vite.config.js
index 627a3196..8d83055e 100644
--- a/repl/vite.config.js
+++ b/repl/vite.config.js
@@ -4,4 +4,7 @@ import react from '@vitejs/plugin-react';
 // https://vitejs.dev/config/
 export default defineConfig({
   plugins: [react()],
+  build: {
+    outDir: '../out',
+  },
 });
diff --git a/tutorial/vite.config.js b/tutorial/vite.config.js
index 67e17b94..48c0dc0a 100644
--- a/tutorial/vite.config.js
+++ b/tutorial/vite.config.js
@@ -14,8 +14,12 @@ const options = {
 // https://vitejs.dev/config/
 export default defineConfig({
   plugins: [react(), mdx(options)],
+  build: {
+    outDir: '../out/tutorial',
+  },
+  base: '/tutorial/',
 });
 
 // jsxRuntime:'classic' to prevent "jsxDevRuntime.exports.jsxDEV is not a function" for dev mode
 // mode: 'development',
-// react({ jsxRuntime: 'classic' }),
\ No newline at end of file
+// react({ jsxRuntime: 'classic' }),