Err 503 on adding datapoint to a Flow requiring a signed payload

[mathcoll]

Describe the bug
Err 503 on adding datapoint to a Flow requiring a signed payload

To Reproduce
Steps to reproduce the behavior:

1. create a Flow with attribute: "require_signed": true and an object having its own secret_key
2. POST /data to that Flow without any signed payload
3. Server is currently responding a 503

at signatureCheck (/media/Documents/Projets/2019/internetcollaboratif.info/t6/routes/data.js:98:7) at nextTask (/media/Documents/Projets/2019/internetcollaboratif.info/t6/node_modules/async/dist/async.js:5756:27) at next (/media/Documents/Projets/2019/internetcollaboratif.info/t6/node_modules/async/dist/async.js:5764:13) ] Trace: Error: Error: Callback was already called. at process.<anonymous> (/media/Documents/Projets/2019/internetcollaboratif.info/t6/node_modules/libnmap/lib/libnmap.js:116:17) at process.emit (node:events:388:22) at process._fatalException (node:internal/process/execution:163:25) at processPromiseRejections (node:internal/process/promises:227:11) at processTicksAndRejections (node:internal/process/task_queues:94:32) at process.<anonymous> (/media/Documents/Projets/2019/internetcollaboratif.info/t6/node_modules/libnmap/lib/libnmap.js:116:11) at process.emit (node:events:388:22) at process._fatalException (node:internal/process/execution:163:25) at processPromiseRejections (node:internal/process/promises:227:11) at processTicksAndRejections (node:internal/process/task_queues:94:32) 02/Oct/2021:21:02:56 +0200 [0m[31m[ERROR] [

Expected behavior
201 status code and success response

[mathcoll]

Fixed 71a4b4b and 59e8494