Error: Property failed after 1 tests { seed: -1158873954, path: "0:0:0:0:0", endOnFailure: true } Counterexample: [[1,0,0],[undefined,undefined,undefined],undefined] Shrunk 4 time(s) Got error: unsupported operand type(s) for -: 'int' and 'NoneType' at WebSocket.handleMessage (/home/runner/work/nvector-js/nvector-js/test/nvector-test-api.ts:82:18) at WebSocket.emit (node:events:518:28) at Receiver.receiverOnMessage (/home/runner/work/nvector-js/nvector-js/node_modules/ws/lib/websocket.js:1209:20) at Receiver.emit (node:events:518:28) at Receiver.dataMessage (/home/runner/work/nvector-js/nvector-js/node_modules/ws/lib/receiver.js:603:14) at /home/runner/work/nvector-js/nvector-js/node_modules/ws/lib/receiver.js:534:12 at /home/runner/work/nvector-js/nvector-js/node_modules/ws/lib/permessage-deflate.js:309:9 at /home/runner/work/nvector-js/nvector-js/node_modules/ws/lib/permessage-deflate.js:392:7 at afterWrite (node:internal/streams/writable:701:5) at onwrite (node:internal/streams/writable:679:7) Hint: Enable verbose mode in order to have the list of all failing values encountered during the run ❯ WebSocket.handleMessage test/nvector-test-api.ts:82:18 ❯ WebSocket.emit node:events:518:28 ❯ Receiver.receiverOnMessage node_modules/ws/lib/websocket.js:1209:20 ❯ Receiver.emit node:events:518:28 ❯ Receiver.dataMessage node_modules/ws/lib/receiver.js:603:14 ❯ node_modules/ws/lib/receiver.js:534:12 ❯ node_modules/ws/lib/permessage-deflate.js:309:9 ❯ node_modules/ws/lib/permessage-deflate.js:392:7 ❯ buildError node_modules/fast-check/lib/esm/check/runner/utils/RunDetailsFormatter.js:126:15 ❯ asyncThrowIfFailed node_modules/fast-check/lib/esm/check/runner/utils/RunDetailsFormatter.js:143:11