JEST tests complete successfully but returns exit status 1

I run JEST tests using npm run test:jest and the corresponding entry in package.json is

"test:jest": "jest --config=./jest.config.js",

All tests run successfully, but returns with exit code 1

Test Suites: 1 skipped, 106 passed, 106 of 107 total
Tests:       10 skipped, 657 passed, 667 total
Snapshots:   14 files obsolete, 0 total
Time:        34.453s
Ran all test suites.
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! @vc/toolchain@3.3.0 test:jest: `jest --config=./jest.config.js`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the @vc/toolchain@3.3.0 test:jest script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR!     /home/.npm/_logs/2019-12-18T13_01_11_869Z-debug.log

10 silly lifecycle @vc/toolchain@3.3.0~test:jest: Args: [ '-c', 'jest --config=./jest.config.js' ]
11 silly lifecycle @vc/toolchain@3.3.0~test:jest: Returned: code: 1  signal: null
12 info lifecycle @vc/toolchain@3.3.0~test:jest: Failed to exec test:jest script
13 verbose stack Error: @vc/toolchain@3.3.0 test:jest: `jest --config=./jest.config.js`
13 verbose stack Exit status 1
13 verbose stack     at EventEmitter.<anonymous> (/usr/local/lib/node_modules/npm/node_modules/npm-lifecycle/index.js:332:16)
13 verbose stack     at emitTwo (events.js:126:13)
13 verbose stack     at EventEmitter.emit (events.js:214:7)
13 verbose stack     at ChildProcess.<anonymous> (/usr/local/lib/node_modules/npm/node_modules/npm-lifecycle/lib/spawn.js:55:14)
13 verbose stack     at emitTwo (events.js:126:13)
13 verbose stack     at ChildProcess.emit (events.js:214:7)
13 verbose stack     at maybeClose (internal/child_process.js:915:16)
13 verbose stack     at Process.ChildProcess._handle.onexit (internal/child_process.js:209:5)
14 verbose pkgid @vc/toolchain@3.3.0
15 verbose cwd /workspace/vc.src/vco/src/server/node
16 verbose Linux 3.13.0-163-generic
17 verbose argv "/usr/local/bin/node" "/usr/local/bin/npm" "run" "test:jest"
18 verbose node v8.17.0
19 verbose npm  v6.13.4
20 error code ELIFECYCLE
21 error errno 1
22 error @vc/toolchain@3.3.0 test:jest: `jest --config=./jest.config.js`
22 error Exit status 1
23 error Failed at the @vc/toolchain@3.3.0 test:jest script.
23 error This is probably not a problem with npm. There is likely additional logging output above.
24 verbose exit [ 1, true ]

I am not sure why the process exits with status code 1 even though all tests pass.

[corsik]

Snapshots: 3 obsolete, 26 passed, 26 total obsolete - are the cause of the error, after their removal, the error is gone.

[thymikee]

Repro please, or it didn’t happen