chore: improve import-analysis error message for inline <script> HTML termination #21150

packages/vite/src/node/plugins/importAnalysis.ts

@@ -891,11 +891,24 @@ export function createParseErrorInfo(
           importer,
         )}" to \`assetsInclude\` in your configuration.`
 
+  const htmlScriptNote =
+    `\n\nNote: If this code is inside an inline <script> in an HTML file, ` +
+    `the literal sequence \`</script>\` (even inside a string or template literal)` +
+    ` will terminate the script early due to HTML parsing rules. This results in ` +
+    `truncated/invalid JS being passed to import analysis. To fix, escape the slash ` +
+    `like \`<\\/script>\` in the HTML source, break the sequence (e.g. \`"</" + "script>"\`), ` +
+    `or move the code to an external .js/.ts module.`
+
+  const isHtmlImporter = !!importer && /\.html?$/i.test(importer)
+
+  const finalMessage =
+    `Failed to parse source for import analysis because the content ` +
+    `contains invalid JS syntax. ` +
+    msg +
+    (isHtmlImporter ? htmlScriptNote : '')
+
   return {
-    message:
-      `Failed to parse source for import analysis because the content ` +
-      `contains invalid JS syntax. ` +
-      msg,
+    message: finalMessage,
     showCodeFrame: !probablyBinary,
   }
 }

packages/vite/src/node/server/environment.ts

@@ -1,6 +1,6 @@
 import colors from 'picocolors'
-import type { FSWatcher } from '#dep-types/chokidar'
 import type { FetchFunctionOptions, FetchResult } from 'vite/module-runner'
+import type { FSWatcher } from '#dep-types/chokidar'
 import { BaseEnvironment } from '../baseEnvironment'
 import type {
   EnvironmentOptions,

packages/vite/src/node/server/index.ts

@@ -13,9 +13,9 @@ import colors from 'picocolors'
 import chokidar from 'chokidar'
 import launchEditorMiddleware from 'launch-editor-middleware'
 import type { SourceMap } from 'rollup'
+import type { ModuleRunner } from 'vite/module-runner'
 import type { FSWatcher, WatchOptions } from '#dep-types/chokidar'
 import type { Connect } from '#dep-types/connect'
-import type { ModuleRunner } from 'vite/module-runner'
 import type { CommonServerOptions } from '../http'
 import {
   httpServerStart,

packages/vite/src/node/ssr/runtime/serverModuleRunner.ts

@@ -1,11 +1,11 @@
 import { existsSync, readFileSync } from 'node:fs'
-import type { HotPayload } from '#types/hmrPayload'
 import { ModuleRunner, createNodeImportMeta } from 'vite/module-runner'
 import type {
   ModuleEvaluator,
   ModuleRunnerHmr,
   ModuleRunnerOptions,
 } from 'vite/module-runner'
+import type { HotPayload } from '#types/hmrPayload'
 import type { DevEnvironment } from '../../server/environment'
 import type {
   HotChannelClient,