Fix Network.post() silently dropping falsy-but-defined params from FormData

[Beamanator]

Fix Network.post() silently dropping falsy-but-defined values from FormData.

The check if (!value) is a falsy guard — it drops false, 0, '', null, and undefined. For multipart requests (those containing a File or Blob), this meant parameters like csrfToken could be silently omitted from the FormData body if their value was falsy.

The keepalive() method in the same file already uses the correct guard if (value === undefined). This aligns post() to match.

History: This fix was originally made in 2020 (commit 832cd5a) and then reverted 10 minutes later in the same PR (#262) as "an unnecessary change" with no further explanation. The revert left keepalive() with the correct undefined check while post() regressed back to the falsy check.

Behavioral change for callers: Boolean false, null, 0, and '' values were previously dropped from FormData silently. After this fix they are included and serialized by FormData (false → 'false', null → 'null', etc.). Audited Web-Expensify callers of file upload commands — the affected falsy values are boolean false (e.g. shouldSkipSmartScan, isManualRequestScan) and undefined. PHP's Str::toBool() (used by Request::getBool) calls filter_var($input, FILTER_VALIDATE_BOOLEAN) which correctly maps the string "false" → false, so behavior is unchanged.

Fixed Issues

$ https://github.com/Expensify/Expensify/issues/535855

Tests

1. No existing automated test coverage for the FormData construction path.
2. Verified by code trace: post() only uses FormData as settings.data when a File or Blob is present in parameters (i.e., receipt/attachment upload commands). Regular API calls are unaffected — they use settings.data = parameters (the plain object).

QA

Regression — receipt upload still works end-to-end:

1. Log in to OldDot (expensify.com)
2. Open DevTools → Network tab, filter by Expense_Create
3. Go to the Expenses page and click the SmartScan / upload receipt button
4. Upload any image file (jpg, png)
5. In the Network tab, find the Expense_Create POST request
6. Click the request → Payload tab → view the multipart form data body
7. Confirm csrfToken is present with a non-empty value
8. Confirm isManualRequestScan is present with value "false" (previously this was dropped; now it is sent as the string "false", which PHP correctly interprets as false)
9. Confirm the receipt upload succeeds and the expense appears in the list

Regression — non-file API calls unaffected:

1. With DevTools open, perform any regular (non-file) API action (e.g., submit a report)
2. Confirm the request does not use multipart/form-data (it should be application/x-www-form-urlencoded or JSON)
3. Confirm the action succeeds normally

[Beamanator]

@codex review

[chatgpt-codex-connector]

To use Codex here, create a Codex account and connect to github.

[os-botify]

🚀 Published to npm in 2.0.177 🎉