diff --git a/e2e/cases/preact/prefresh-context/index.test.ts b/e2e/cases/preact/prefresh-context/index.test.ts
index fbda720e8f..15ec83a5e6 100644
--- a/e2e/cases/preact/prefresh-context/index.test.ts
+++ b/e2e/cases/preact/prefresh-context/index.test.ts
@@ -44,8 +44,8 @@ export default B;
   );
 
   await page.waitForFunction(() => {
-    const aText = document.querySelector('#A')!.textContent;
-    const bText = document.querySelector('#B')!.textContent;
+    const aText = document.querySelector('#A')?.textContent;
+    const bText = document.querySelector('#B')?.textContent;
 
     return (
       // the state (count) of A should be kept
diff --git a/e2e/cases/preact/prefresh-disabled/index.test.ts b/e2e/cases/preact/prefresh-disabled/index.test.ts
index 24d8b72aa9..8e84a15ada 100644
--- a/e2e/cases/preact/prefresh-disabled/index.test.ts
+++ b/e2e/cases/preact/prefresh-disabled/index.test.ts
@@ -43,8 +43,8 @@ export default B;
   );
 
   await page.waitForFunction(() => {
-    const aText = document.querySelector('#A')!.textContent;
-    const bText = document.querySelector('#B')!.textContent;
+    const aText = document.querySelector('#A')?.textContent;
+    const bText = document.querySelector('#B')?.textContent;
 
     return (
       // the state (count) of A should not be kept
diff --git a/e2e/cases/preact/prefresh/index.test.ts b/e2e/cases/preact/prefresh/index.test.ts
index d1a7f9472a..065df0ab94 100644
--- a/e2e/cases/preact/prefresh/index.test.ts
+++ b/e2e/cases/preact/prefresh/index.test.ts
@@ -43,8 +43,8 @@ export default B;
   );
 
   await page.waitForFunction(() => {
-    const aText = document.querySelector('#A')!.textContent;
-    const bText = document.querySelector('#B')!.textContent;
+    const aText = document.querySelector('#A')?.textContent;
+    const bText = document.querySelector('#B')?.textContent;
 
     return (
       // the state (count) of A should be kept
diff --git a/e2e/cases/solid/hmr/index.test.ts b/e2e/cases/solid/hmr/index.test.ts
index 4ecec20b59..1433fb51e5 100644
--- a/e2e/cases/solid/hmr/index.test.ts
+++ b/e2e/cases/solid/hmr/index.test.ts
@@ -43,8 +43,8 @@ export default B;
   );
 
   await page.waitForFunction(() => {
-    const aText = document.querySelector('#A')!.textContent;
-    const bText = document.querySelector('#B')!.textContent;
+    const aText = document.querySelector('#A')?.textContent;
+    const bText = document.querySelector('#B')?.textContent;
 
     return (
       // the state (count) of A should be kept
diff --git a/e2e/scripts/shared.ts b/e2e/scripts/shared.ts
index d5fbe8216c..4c7cbb859c 100644
--- a/e2e/scripts/shared.ts
+++ b/e2e/scripts/shared.ts
@@ -261,11 +261,11 @@ export async function build({
         ([file]) => file.includes('index') && file.endsWith('.js'),
       ) || [];
 
-    assert(name);
+    assert(name && content);
 
     return {
-      content: content!,
-      size: content!.length / 1024,
+      content: content,
+      size: content.length / 1024,
     };
   };
 
diff --git a/packages/compat/plugin-webpack-swc/tests/plugin.test.ts b/packages/compat/plugin-webpack-swc/tests/plugin.test.ts
index 04e3478d4f..3508e62063 100644
--- a/packages/compat/plugin-webpack-swc/tests/plugin.test.ts
+++ b/packages/compat/plugin-webpack-swc/tests/plugin.test.ts
@@ -380,7 +380,8 @@ describe('plugin-webpack-swc', () => {
       const config = (
         await applyPluginConfig(
           (config) => {
-            config.env!.coreJs = '2';
+            config.env ||= {};
+            config.env.coreJs = '2';
             return config;
           },
           UTILS,
@@ -420,8 +421,7 @@ describe('plugin-webpack-swc', () => {
       },
     });
     const config = await rsbuild.unwrapConfig();
-
-    expect(config.module!.rules).toMatchSnapshot();
+    expect(config.module.rules).toMatchSnapshot();
   });
 
   it('should allow to disable transformLodash', async () => {
diff --git a/packages/compat/webpack/tests/initConfigs.test.ts b/packages/compat/webpack/tests/initConfigs.test.ts
index 34b19c4708..1216750dbc 100644
--- a/packages/compat/webpack/tests/initConfigs.test.ts
+++ b/packages/compat/webpack/tests/initConfigs.test.ts
@@ -16,7 +16,8 @@ describe('modifyRsbuildConfig', () => {
           });
 
           api.modifyWebpackChain(() => {
-            config.server!.port = 8899;
+            config.server ||= {};
+            config.server.port = 8899;
           });
         },
       },
diff --git a/packages/core/src/client/overlay.ts b/packages/core/src/client/overlay.ts
index b6ad835a9c..0e09a32a9b 100644
--- a/packages/core/src/client/overlay.ts
+++ b/packages/core/src/client/overlay.ts
@@ -19,10 +19,10 @@ class ErrorOverlay extends HTMLElement {
     const root = this.attachShadow({ mode: 'open' });
     root.innerHTML = html;
 
-    root.querySelector('.close')!.addEventListener('click', this.close);
+    root.querySelector('.close')?.addEventListener('click', this.close);
     // close overlay when click outside
     this.addEventListener('click', this.close);
-    root.querySelector('.container')!.addEventListener('click', (e) => {
+    root.querySelector('.container')?.addEventListener('click', (e) => {
       if (e.target) {
         const { file } = (e.target as HTMLLinkElement).dataset;
         if (file) {
diff --git a/packages/core/src/pluginManager.ts b/packages/core/src/pluginManager.ts
index 90125101d8..9ef8ef24e0 100644
--- a/packages/core/src/pluginManager.ts
+++ b/packages/core/src/pluginManager.ts
@@ -256,7 +256,7 @@ export async function initPlugins({
       continue;
     }
     const { instance, environment } = plugin;
-    await instance.setup(getPluginAPI!(environment));
+    await instance.setup(getPluginAPI(environment));
   }
 
   logger.debug('init plugins done');
diff --git a/packages/core/src/plugins/fileSize.ts b/packages/core/src/plugins/fileSize.ts
index 1ed275d247..1c807445ff 100644
--- a/packages/core/src/plugins/fileSize.ts
+++ b/packages/core/src/plugins/fileSize.ts
@@ -143,7 +143,7 @@ async function printFileSizes(
     });
 
     const exclude = options.exclude ?? excludeAsset;
-    const filteredAssets = origin.assets!.filter((asset) => {
+    const filteredAssets = (origin.assets || []).filter((asset) => {
       const assetInfo: PrintFileSizeAsset = {
         name: asset.name,
         size: asset.size,
diff --git a/packages/core/src/plugins/manifest.ts b/packages/core/src/plugins/manifest.ts
index 33d8da54e6..483cbdc05a 100644
--- a/packages/core/src/plugins/manifest.ts
+++ b/packages/core/src/plugins/manifest.ts
@@ -62,8 +62,10 @@ const generateManifest =
           assets.add(relatedLICENSE);
         }
 
-        for (const auxiliaryFile of file.chunk!.auxiliaryFiles) {
-          assets.add(auxiliaryFile);
+        if (file.chunk) {
+          for (const auxiliaryFile of file.chunk.auxiliaryFiles) {
+            assets.add(auxiliaryFile);
+          }
         }
       }
 
diff --git a/packages/core/tests/mergeConfig.test.ts b/packages/core/tests/mergeConfig.test.ts
index 13b625e4bd..332f1a47d2 100644
--- a/packages/core/tests/mergeConfig.test.ts
+++ b/packages/core/tests/mergeConfig.test.ts
@@ -329,7 +329,7 @@ describe('mergeRsbuildConfig', () => {
       },
     });
 
-    expect(mergedConfig.tools!.rspack.plugins[0] instanceof A).toBeTruthy();
+    expect(mergedConfig.tools?.rspack.plugins[0] instanceof A).toBeTruthy();
   });
 
   test('should merge overrideBrowserslist in environments as expected', async () => {
diff --git a/packages/create-rsbuild/template-vanilla-ts/src/index.ts b/packages/create-rsbuild/template-vanilla-ts/src/index.ts
index 4f3e14e2a2..0c50c63f73 100644
--- a/packages/create-rsbuild/template-vanilla-ts/src/index.ts
+++ b/packages/create-rsbuild/template-vanilla-ts/src/index.ts
@@ -1,8 +1,11 @@
 import './index.css';
 
-document.querySelector('#root')!.innerHTML = `
-<div class="content">
-  <h1>Vanilla Rsbuild</h1>
-  <p>Start building amazing things with Rsbuild.</p>
-</div>
+const rootEl = document.querySelector('#root');
+if (rootEl) {
+  rootEl.innerHTML = `
+  <div class="content">
+    <h1>Vanilla Rsbuild</h1>
+    <p>Start building amazing things with Rsbuild.</p>
+  </div>
 `;
+}
diff --git a/website/docs/en/config/html/tags.mdx b/website/docs/en/config/html/tags.mdx
index 46f7c9042a..56d3461422 100644
--- a/website/docs/en/config/html/tags.mdx
+++ b/website/docs/en/config/html/tags.mdx
@@ -131,7 +131,8 @@ export default {
         // Modify 'a.js' tag
         const target = tags.find((tag) => tag.attrs?.src === 'a.js');
         if (target) {
-          target.attrs!.defer = true;
+          target.attrs ||= {};
+          target.attrs.defer = true;
         }
       },
       (tags) => {
diff --git a/website/docs/en/config/index.mdx b/website/docs/en/config/index.mdx
index 28a113caea..80e8a221d7 100644
--- a/website/docs/en/config/index.mdx
+++ b/website/docs/en/config/index.mdx
@@ -1,6 +1,6 @@
 # Config overview
 
-This page lists all the configurations for Rsbuild. See ["Configure Rsbuild"](/guide/basic/configure-rsbuild) for detail.
+This page lists all the configurations for Rsbuild. See ["Configure Rsbuild"](/guide/basic/configure-rsbuild) for details.
 
 import Overview from '@components/Overview';
 
diff --git a/website/docs/zh/config/html/tags.mdx b/website/docs/zh/config/html/tags.mdx
index f3afae8d43..5a948da0bd 100644
--- a/website/docs/zh/config/html/tags.mdx
+++ b/website/docs/zh/config/html/tags.mdx
@@ -130,7 +130,8 @@ export default {
         // 修改 'a.js' 标签
         const target = tags.find((tag) => tag.attrs?.src === 'a.js');
         if (target) {
-          target.attrs!.defer = true;
+          target.attrs ||= {};
+          target.attrs.defer = true;
         }
       },
       (tags) => {