refactor: silence optString(name, null) Kotlin warnings

[uwayss]

Building the Android modules gives 23 compiler warnings, all the same one:

w: Java type mismatch: inferred type is 'Nothing?', but 'String' was expected

They come from optString(name, null) — optString's fallback param is @NonNull, so passing null warns. 13 in AutoPrefetcher.kt, 10 in NitroWebSocketAutoPrewarmer.kt.

This adds an optStringOrNull() helper to each android package and moves all 23 calls onto it. compileReleaseKotlin on both modules: 23 warnings → 0.

internal fun JSONObject.optStringOrNull(name: String): String? =
  if (isNull(name)) null else optString(name)

isNull() maps both a missing key and an explicit "key": null to null.

A couple of small things:

• NitroWebSocketAutoPrewarmer.kt:206 keeps optString(j, null) — that's the JSONArray overload, no @NonNull, never warned.
• Helper is internal (kept out of the published AAR) and duplicated per package, since the websockets module doesn't depend on the fetch one — same as NitroLogger.kt.

Test plan

• compileReleaseKotlin both modules — 23 → 0
• bun lint, bun typecheck, bun test — all pass

🤖 Generated with Claude Code

[vercel]

@uwayss is attempting to deploy a commit to the Margelo Team on Vercel.

A member of the Team first needs to authorize it.

[riteshshukla04]

Thanks for PR. This is good stuff. I just have 2 issues here

1. Lots of AI slop comments (Max 1 line comment)
2. The check has an issue . Something like {"foo": null} would return empty string in optString

[uwayss]

Both fixed in d4e568e — comments down to one line, and switched to isNull() so {"foo": null} returns null.