'npm audit' is broken since v6.3.0

Environment
Provide version numbers for the following components (information can be retrieved by running tns info in your project folder or by inspecting the package.json of the project):

• CLI: 6.3.0+
• Cross-platform modules:
• Android Runtime:
• iOS Runtime:
• Plugin(s):

Describe the bug
Npm returns the following error when running npm audit on the cloned repo or any other project that has the nativescript cli 6.3.0+ in dependencies/devDependencies:

npm ERR! code ENOAUDIT
npm ERR! audit Your configured registry (https://registry.npmjs.org/) may not support audit requests, or the audit endpoint may be temporarily unavailable.
npm ERR! audit The server said: Invalid package tree, run  npm install  to rebuild your package-lock.json

Full log:

0 info it worked if it ends with ok
1 verbose cli [ '/Users/nsch/.nvm/versions/node/v10.16.0/bin/node',
1 verbose cli   '/Users/nsch/.nvm/versions/node/v10.16.0/bin/npm',
1 verbose cli   'audit' ]
2 info using npm@6.14.2
3 info using node@v10.16.0
4 verbose npm-session 889c098014892da6
5 http fetch POST 400 https://registry.npmjs.org/-/npm/v1/security/audits 480ms
6 verbose stack Error: Your configured registry (https://registry.npmjs.org/) may not support audit requests, or the audit endpoint may be temporarily unavailable.
6 verbose stack The server said: Invalid package tree, run  npm install  to rebuild your package-lock.json
6 verbose stack     at Bluebird.all.spread.then.catch (/Users/nsch/.nvm/versions/node/v10.16.0/lib/node_modules/npm/lib/audit.js:204:18)
6 verbose stack     at tryCatcher (/Users/nsch/.nvm/versions/node/v10.16.0/lib/node_modules/npm/node_modules/bluebird/js/release/util.js:16:23)
6 verbose stack     at Promise._settlePromiseFromHandler (/Users/nsch/.nvm/versions/node/v10.16.0/lib/node_modules/npm/node_modules/bluebird/js/release/promise.js:517:31)
6 verbose stack     at Promise._settlePromise (/Users/nsch/.nvm/versions/node/v10.16.0/lib/node_modules/npm/node_modules/bluebird/js/release/promise.js:574:18)
6 verbose stack     at Promise._settlePromise0 (/Users/nsch/.nvm/versions/node/v10.16.0/lib/node_modules/npm/node_modules/bluebird/js/release/promise.js:619:10)
6 verbose stack     at Promise._settlePromises (/Users/nsch/.nvm/versions/node/v10.16.0/lib/node_modules/npm/node_modules/bluebird/js/release/promise.js:695:18)
6 verbose stack     at _drainQueueStep (/Users/nsch/.nvm/versions/node/v10.16.0/lib/node_modules/npm/node_modules/bluebird/js/release/async.js:138:12)
6 verbose stack     at _drainQueue (/Users/nsch/.nvm/versions/node/v10.16.0/lib/node_modules/npm/node_modules/bluebird/js/release/async.js:131:9)
6 verbose stack     at Async._drainQueues (/Users/nsch/.nvm/versions/node/v10.16.0/lib/node_modules/npm/node_modules/bluebird/js/release/async.js:147:5)
6 verbose stack     at Immediate.Async.drainQueues [as _onImmediate] (/Users/nsch/.nvm/versions/node/v10.16.0/lib/node_modules/npm/node_modules/bluebird/js/release/async.js:17:14)
6 verbose stack     at runCallback (timers.js:705:18)
6 verbose stack     at tryOnImmediate (timers.js:676:5)
6 verbose stack     at processImmediate (timers.js:658:5)
7 verbose cwd /Users/nsch/test/test-package
8 verbose Darwin 18.7.0
9 verbose argv "/Users/nsch/.nvm/versions/node/v10.16.0/bin/node" "/Users/nsch/.nvm/versions/node/v10.16.0/bin/npm" "audit"
10 verbose node v10.16.0
11 verbose npm  v6.14.2
12 error code ENOAUDIT
13 error audit Your configured registry (https://registry.npmjs.org/) may not support audit requests, or the audit endpoint may be temporarily unavailable.
13 error audit The server said: Invalid package tree, run  npm install  to rebuild your package-lock.json
14 verbose exit [ 1, true ]

To Reproduce
Add "nativescript": "6.3.0" to any project, run npm install with a clean node_modules folder & run npm audit. Or clone this repo and checkout to any version that is 6.3.0 or higher, run npm install and then run npm audit. On version 6.2.1 everything seems to be working.

Expected behavior
Be able to see a normal npm audit output.

Reproduce the failure by installing NativeScript CLI 6.3.0 or later in a clean project, then run npm audit. Compare the dependency and lockfile trees from 6.2.1 and 6.3.0 to identify what makes npm reject the package tree. Done means npm audit completes and shows its normal output for an affected project.