feat(server-utils): Warn when bundler config has instrumented module in external

[timfish]

If users have a library we instrument in their bundler external config we should warn them about the fact that this stops it from getting instrumented!

[sentry]

Bug: The code doesn't handle RegExp objects in Vite's ssr.external configuration, causing a TypeError when startsWith() is called on a RegExp and crashing the build.
_{Severity: HIGH}

Suggested Fix

Before calling externalEntryMatchesModule, add a type guard to ensure the entry from the external array is a string. Regular expressions should be handled separately or skipped, similar to how the Webpack bundler implementation handles them. For example, wrap the call in an if (typeof entry === 'string') block.

Prompt for AI Agent

Review the code at the location below. A potential bug has been identified by an AI
agent. Verify if this is a real issue. If it is, propose a fix; if not, explain why it's
not valid.

Location: packages/server-utils/src/orchestrion/bundler/vite.ts#L43-L44

Potential issue: The code in `vite.ts` processes the `ssr.external` configuration
option, which can be an array of strings and/or `RegExp` objects according to Vite's
documentation. The implementation iterates through this array and passes each `entry` to
the `externalEntryMatchesModule` function. This helper function incorrectly assumes the
`entry` is always a string and calls `.startsWith()` on it. If a user configures
`ssr.external` with a `RegExp` (e.g., `[/^mysql/]`), the code will attempt to call
`.startsWith()` on the `RegExp` object, resulting in a `TypeError: entry.startsWith is
not a function` and causing the build process to crash.

_{Did we get this right? 👍 / 👎 to inform future reviews.}

[timfish]

Not a valid issue. ssr.external is typed string[] | true in every Vite major from 6 through 8 (current latest 8.1.5) — RegExp is only accepted in ssr.noExternal, which this code never reads. The same holds for the Environment API successor, resolve.external. Since the Array.isArray check on line 42 already filters out true/undefined, every entry reaching externalEntryMatchesModule is a string per Vite's API contract, so the described TypeError cannot occur with a valid config. The finding conflates the external and noExternal signatures.