React: Fix runtime TypeScript import crash in non-TypeScript projects

[Copilot]

@storybook/react was crashing with ERR_MODULE_NOT_FOUND: Cannot find package 'typescript' in projects that don't have TypeScript installed, because getTsConfig in reactDocgen/utils.ts unconditionally called await import('typescript') before checking whether a tsconfig.json even existed. An accidental console.log({ tsconfigPath }) was also left in.

Changes

• reactDocgen/utils.ts: Refactored getTsConfig to use findTsconfigPath (backed by find-up, no TypeScript required) as a pre-check before dynamically importing TypeScript:
  • No tsconfig.json → returns {} immediately, TypeScript is never imported
  • tsconfig.json found → imports TypeScript and parses compiler options
  • TypeScript not installed but tsconfig.json exists → caught by the existing try/catch, returns {}
• Removed the stray console.log({ tsconfigPath }) debug artifact

// Before: always imports typescript first
const ts = await import('typescript');
const tsconfigPath = ts.findConfigFile(process.cwd(), ts.sys.fileExists);
console.log({ tsconfigPath }); // leftover debug

// After: check for tsconfig without touching TypeScript
const tsconfigPath = findTsconfigPath(process.cwd());
if (!tsconfigPath) return {};
const ts = await import('typescript'); // only reached if tsconfig.json exists

Original prompt

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This section details on the original issue you should resolve

<issue_title>[Bug]: @storybook/react runtime import of typescript breaks when TS is not installed</issue_title>
<issue_description>### Describe the bug

While running Storybook in a project that does not use TypeScript, we’re hitting a runtime error caused by a missing typescript dependency.

Error

Error [ERR_MODULE_NOT_FOUND]: Cannot find package 'typescript'

Either:

• typescript should be declared as a dependency (or peerDependency) if it's required at runtime
• The import should be optional / lazy / guarded so that non-TypeScript projects can run without it

Reproduction link

N/A

Reproduction steps

Package: @storybook/nextjs
Version: 10.3.3
Transitive dependency: @storybook/react
Environment: non-TypeScript project (no typescript installed)

System

│  Storybook Environment Info:
│

│  System:
│  OS: macOS 26.3.1
│  CPU: (10) arm64 Apple M1 Pro
│  Shell: 5.9 - /bin/zsh
│  Binaries:
│  Node: 24.8.0 - /opt/homebrew/bin/node
│  Yarn: 1.22.22 - /opt/homebrew/bin/yarn <----- active
│  npm: 11.6.0 - /opt/homebrew/bin/npm
│  pnpm: 10.28.2 - /opt/homebrew/bin/pnpm
│  Browsers:
│  Safari: 26.3.1

Additional context

• This seems to come from the build output rather than explicit source usage
• Likely related to docgen / TypeScript tooling being bundled
• My guess is this goes unnoticed because most projects already have typescript installed

Workaround

Installing typescript fixes the issue for the version 10.3.3:

npm install -D typescript

Suggestion

It might be worth reviewing how typescript is bundled / referenced in @storybook/react to avoid requiring it implicitly at runtime.</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes [Bug]: @storybook/react runtime import of typescript breaks when TS is not installed #34340

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