Cannot read property 'length' of undefined (npm 7.0.8)

[lesyk-lesyk]

An error occurs during the installation of a new package.
Maybe relates to #2116

➜ git:(chore/npm-test) ✗ npm i --save-dev @graphql-codegen/typescript
npm ERR! code ERESOLVE
npm ERR! Cannot read property 'length' of undefined

npm ERR! A complete log of this run can be found in:
npm ERR!     /Users/XXX/.npm/_logs/2020-11-06T11_25_39_984Z-debug.log

➜ node --version
v15.1.0

➜  npm --version
7.0.8

MacOS Catalina 10.15.7

Full log:
2020-11-06T11_25_39_984Z-debug.log

[darcyclarke]

Hey @okachynskyy! Sorry to hear you're having troubles. I just tried replicating this error & couldn't on the exact same setup (ie. os/node/npm version). Potentially, another dep you have in your tree is causing the problem or maybe has a peer conflict that can't be resolved (which is what the debug log seems to allude to). Can you try running that install again with either --force or using the legacy install behaviour w/ --legacy-peer-deps & see if that works/fixes anything?

[Kichrum]

Have the same error on both 7.0.8 and 7.0.9 with a completely another setup (Angular 9 project), the error is quite not self-explanatory

TypeError: Cannot read property 'length' of undefined
  at explainDependents (/node/v15.1.0/lib/node_modules/npm/lib/utils/explain-dep.js:68:19)

--legacy-peer-deps fixes it, but I need a proper solution :)

[ebiton-eig]

I have the same problem with the package @angular/core (npm 7.0.9 and nodejs 15.1.0).

I used the command : ng update @angular/core :

`Using package manager: 'npm'
Collecting installed dependencies...
Found 55 dependencies.
Fetching dependency metadata from registry...
Updating package.json with dependency @angular/compiler-cli @ "10.2.2" (was "10.2.0")...
Updating package.json with dependency @angular/language-service @ "10.2.2" (was "10.2.0")...
Updating package.json with dependency @types/jasmine @ "3.6.1" (was "3.6.0")...
Updating package.json with dependency @angular/animations @ "10.2.2" (was "10.2.0")...
Updating package.json with dependency @angular/common @ "10.2.2" (was "10.2.0")...
Updating package.json with dependency @angular/compiler @ "10.2.2" (was "10.2.0")...
Updating package.json with dependency @angular/core @ "10.2.2" (was "10.2.0")...
Updating package.json with dependency @angular/forms @ "10.2.2" (was "10.2.0")...
Updating package.json with dependency @angular/localize @ "10.2.2" (was "10.2.0")...
Updating package.json with dependency @angular/platform-browser-dynamic @ "10.2.2" (was "10.2.0")...
Updating package.json with dependency @angular/router @ "10.2.2" (was "10.2.0")...
Updating package.json with dependency @angular/service-worker @ "10.2.2" (was "10.2.0")...
Updating package.json with dependency @ng-bootstrap/ng-bootstrap @ "8.0.0" (was "7.0.0")...
UPDATE package.json (2957 bytes)
\ Installing packages...npm ERR! code ERESOLVE
npm ERR! Cannot read property 'length' of undefined

npm ERR! C:\Users\edoua\AppData\Local\npm-cache_logs\2020-11-09T08_10_59_399Z-debug.log
× Package install failed, see above.
× Migration failed. See above for further details.`

2020-11-09T08_10_59_399Z-debug.log

[simllll]

Same with latest npm (7.0.9) and --force flag:

134 timing idealTree Completed in 15778ms
135 timing command:install Completed in 15780ms
136 verbose stack TypeError: Cannot read property 'length' of undefined
136 verbose stack     at explainDependents (/usr/local/lib/node_modules/npm/lib/utils/explain-dep.js:68:19)
136 verbose stack     at explainFrom (/usr/local/lib/node_modules/npm/lib/utils/explain-dep.js:95:5)
136 verbose stack     at explainEdge (/usr/local/lib/node_modules/npm/lib/utils/explain-dep.js:87:5)
136 verbose stack     at /usr/local/lib/node_modules/npm/lib/utils/explain-dep.js:59:18
136 verbose stack     at Array.map (<anonymous>)
136 verbose stack     at explainDependents (/usr/local/lib/node_modules/npm/lib/utils/explain-dep.js:59:6)
136 verbose stack     at explainNode (/usr/local/lib/node_modules/npm/lib/utils/explain-dep.js:13:3)
136 verbose stack     at explainEresolve (/usr/local/lib/node_modules/npm/lib/utils/explain-eresolve.js:24:24)
136 verbose stack     at explain (/usr/local/lib/node_modules/npm/lib/utils/explain-eresolve.js:64:38)
136 verbose stack     at EventEmitter.log.warn (/usr/local/lib/node_modules/npm/lib/utils/setup-log.js:20:23)
137 verbose cwd /home/simon/Dev/hokify/hokify-server
138 verbose Linux 5.4.0-52-generic
139 verbose argv "/usr/local/bin/node" "/usr/local/bin/npm" "install" "--unsafe-perm=true" "--allow-root"
140 verbose node v14.15.0
141 verbose npm  v7.0.9
142 error Cannot read property 'length' of undefined
143 verbose exit 1

But it seems it's happening in the bootstrap phase of lerna, if I adapt the paramters for the install paramter there, it also fails. Same stack trace:

136 verbose stack TypeError: Cannot read property 'length' of undefined
136 verbose stack     at explainDependents (/usr/local/lib/node_modules/npm/lib/utils/explain-dep.js:68:19)
136 verbose stack     at explainFrom (/usr/local/lib/node_modules/npm/lib/utils/explain-dep.js:95:5)
136 verbose stack     at explainEdge (/usr/local/lib/node_modules/npm/lib/utils/explain-dep.js:87:5)
136 verbose stack     at /usr/local/lib/node_modules/npm/lib/utils/explain-dep.js:59:18
136 verbose stack     at Array.map (<anonymous>)
136 verbose stack     at explainDependents (/usr/local/lib/node_modules/npm/lib/utils/explain-dep.js:59:6)
136 verbose stack     at explainNode (/usr/local/lib/node_modules/npm/lib/utils/explain-dep.js:13:3)
136 verbose stack     at explainEresolve (/usr/local/lib/node_modules/npm/lib/utils/explain-eresolve.js:24:24)
136 verbose stack     at explain (/usr/local/lib/node_modules/npm/lib/utils/explain-eresolve.js:64:38)
136 verbose stack     at EventEmitter.log.warn (/usr/local/lib/node_modules/npm/lib/utils/setup-log.js:20:23)
137 verbose cwd /home/simon/Dev/hokify/hokify-server
138 verbose Linux 5.4.0-52-generic
139 verbose argv "/usr/local/bin/node" "/usr/local/bin/npm" "install" "--force"
140 verbose node v14.15.0
141 verbose npm  v7.0.9
142 error Cannot read property 'length' of undefined
143 verbose exit 1

The object that fails (explain-dep.js:68):

dependents[i] {
  type: 'dev',
  name: 'ts-loader',
  spec: '^8.0.10',
  from: { location: '/home/simon/Dev/hokify/hokify-server' }
}

it seems the from has no "name" property.

[isaacs]

Can you share your package.json file and/or package-lock.json?

[isaacs]

Nevermind, found it. Fixed on #2156.

[hiepxanh]

hope it will be fix soon, have the same error on 7.0.10 version

[rishabhpoddar]

I'm having this issue with all versions >= 7.0.7 as well.