issues about std_dev case: Cannot read property 'length' of undefined

[serein-dream]

As title, I have run successfully in count and sum,but when i run in std_dev and mean, it meet error :

(node:1327352) UnhandledPromiseRejectionWarning: TypeError: Cannot read property 'length' of undefined
at __unwipe (/conclave-master/jiff/lib/client/protocols/arrays/open.js:60:30)
at open_ND_array (/conclave-master/jiff/lib/client/protocols/arrays/open.js:69:7)
at open (/conclave-master/demo/data/example-jiff-job-1/mpc.js:631:34)
at /conclave-master/demo/data/example-jiff-job-1/mpc.js:696:28
at processTicksAndRejections (internal/process/task_queues.js:95:5)
(Use node --trace-warnings ... to show where the warning was created)
(node:1327352) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag --unhandled-rejections=strict (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 2)
(node:1327352) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

and

(node:1327352) UnhandledPromiseRejectionWarning: TypeError: Cannot read property 'length' of undefined
at stdDev (/conclave-master/demo/data/example-jiff-job-1/mpc.js:604:34)
at runMicrotasks ()
at processTicksAndRejections (internal/process/task_queues.js:95:5)
(node:1327352) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag --unhandled-rejections=strict (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 3)

how can i slove it? Could you please give a sample test example for std_dev
Looking for your help sincerely!