Make error about --dev more obvious.

[NikitaIT]

Prerequisites

• I have written a descriptive issue title
• I have searched existing issues to ensure the bug has not already been reported

Fastify version

5.6.0

Plugin version

8.2.0

Node.js version

24

Operating system

macOS

Operating system version (i.e. 20.04, 11.3, 10)

.

Description

console.warn(
      `Failed to load cached Vite configuration from ${viteConfigDistFile}`,
);

I get it with platformatic start / wattpm devon react-typescript demo from this repo demos.

It was not clear that platformatic start would run it in prod mode, and in prod mode it requires to have a dist.

Well, my old dev command was tsx src/server.ts --dev. And this was expected:

{
  // TODO handle via CLI path argument with proper resolve
  root: resolve(import.meta.dirname, ".."),
  distDir: import.meta.dirname, // This file will also live in the dist folder when built
  renderer: "@fastify/react",
+  dev: true,
};

Link to code that reproduces the bug

.

Expected Behavior

console.error(
      `Failed to load cached Vite configuration from ${viteConfigDistFile}. Production mode requires app to be compiled to dist. If it's not expected, please, provide 'dev' option to Vite config.`,
);