How do I Properly run NPM Install in Visual Studio Team Services Build Agent - npm

Question

I'm having trouble setting up an NPM task for an automated build in Visual Studio Team Services (previously Visual Studio Online). There are two problems:
Cache locking errors (shown below).
It is painfully slow -- 45+ minutes for a dozen or so packages.
I added the --cache argument but that did not seem to help.
npm install --dev --cache $(Agent.BuildDirectory)\b
The binaries folder seems like the right spot for the cache, but honestly, I'm not sure. Some documentation here:
https://msdn.microsoft.com/Library/vs/alm/Build/scripts/variables#AgentVariables
I appreciate any advice...
Current Config:
Build console output:
Set workingFolder to default: C:\LR\MMS\Services\Mms\TaskAgentProvisioner\Tools\agents\1.97.1\tasks\Npm\0.2.7
##[debug]check path : C:\LR\MMS\Services\Mms\TaskAgentProvisioner\Tools\agents\1.97.1\tasks\Npm\0.2.7\task.json
##[debug]set resource file to: C:\LR\MMS\Services\Mms\TaskAgentProvisioner\Tools\agents\1.97.1\tasks\Npm\0.2.7\task.json
##[debug]system.culture=en-US
##[debug]check path : C:\Program Files\nodejs\npm.cmd
##[debug]npm=C:\Program Files\nodejs\npm.cmd
##[debug]cwd=C:\a\1\s\com.example.web
##[debug]path exists: C:\a\1\s\com.example.web
##[debug]command=install
##[debug]C:\Program Files\nodejs\npm.cmd arg: install
##[debug]arguments=--dev --cache C:\a\1\b
##[debug]C:\Program Files\nodejs\npm.cmd arg: --dev --cache C:\a\1\b
##[debug]exec tool: C:\Program Files\nodejs\npm.cmd
##[debug]Arguments:
##[debug] install
##[debug] --dev
##[debug] --cache
##[debug] C:\a\1\b
[command]C:\Program Files\nodejs\npm.cmd install --dev --cache C:\a\1\b
npm WARN deprecated graceful-fs#3.0.8: graceful-fs version 3 and before will fail on newer node releases. Please update to graceful-fs#^4.0.0 as soon as possible.
npm WARN deprecated sf-lint#1.0.2: Use eslint-config-simplifield instead.
npm WARN deprecated lodash#2.4.1: lodash#<3.0.0 is no longer maintained. Upgrade to lodash#^4.0.0.
npm WARN deprecated lodash#0.9.2: Grunt needs your help! See https://github.com/gruntjs/grunt/issues/1403.
npm ERR! addLocal Could not install C:\a\1\s\com.example.web\#shinnn\eslint-config#>=0.0.5 <0.0.6\fixtures
npm WARN deprecated phantomjs#2.1.3: Package renamed to phantomjs-prebuilt. Please update 'phantomjs' package references to 'phantomjs-prebuilt'
npm WARN peerDependencies The peer dependency qunitjs#^1.14.0 included from karma-qunit will no
npm WARN peerDependencies longer be automatically installed to fulfill the peerDependency
npm WARN peerDependencies in npm 3+. Your application will need to depend on it explicitly.
npm WARN package.json Dependency 'mocha' exists in both dependencies and devDependencies, using 'mocha#*' from dependencies
npm WARN package.json Dependency 'mocha' exists in both dependencies and devDependencies, using 'mocha#*' from dependencies
npm ERR! addLocal Could not install C:\a\1\s\com.example.web\#shinnn\eslint-config#>=0.0.4 <0.0.5\fixtures
> cson#1.6.2 preinstall C:\a\1\s\com.example.web\node_modules\gulp-uglify\node_modules\uglify-save-license\node_modules\grunt-replace\node_modules\applause\node_modules\cson
> node ./cyclic.js
npm WARN locking Error: EMFILE, open 'C:\a\1\b\_locks\strip-ansi-0bb45da2369f5768.lock.STALE.STALE.STALE'
npm WARN locking at Error (native)
npm WARN locking C:\a\1\b\_locks\strip-ansi-0bb45da2369f5768.lock failed { [Error: EMFILE, open 'C:\a\1\b\_locks\strip-ansi-0bb45da2369f5768.lock.STALE.STALE.STALE']
npm WARN locking errno: -4066,
npm WARN locking code: 'EMFILE',
npm WARN locking path: 'C:\\a\\1\\b\\_locks\\strip-ansi-0bb45da2369f5768.lock.STALE.STALE.STALE' }
npm ERR! Windows_NT 6.3.9600
npm ERR! argv "C:\\Program Files\\nodejs\\\\node.exe" "C:\\Program Files\\nodejs\\node_modules\\npm\\bin\\npm-cli.js" "install" "--dev" "--cache" "C:\\a\\1\\b"
npm ERR! node v0.12.7
npm ERR! npm v2.11.3
2016-03-30T14:15:17.4509244Z npm ERR! Attempt to unlock C:\a\1\s\com.example.web\node_modules\gulp-imagemin\node_modules\imagemin-pngquant\node_modules\pngquant-bin\node_modules\compare-size\node_modules\ava\node_modules\chalk\node_modules\strip-ansi, which hasn't been locked
npm ERR!
npm ERR! If you need help, you may report this error at:
npm ERR! <https://github.com/npm/npm/issues>
npm WARN locking Error: EMFILE, open 'C:\a\1\b\_locks\ansi-styles-cedcc1e1e4774cd0.lock.STALE.STALE.STALE'
npm WARN locking at Error (native)
npm WARN locking C:\a\1\b\_locks\ansi-styles-cedcc1e1e4774cd0.lock failed { [Error: EMFILE, open 'C:\a\1\b\_locks\ansi-styles-cedcc1e1e4774cd0.lock.STALE.STALE.STALE']
npm WARN locking errno: -4066,
npm WARN locking code: 'EMFILE',
npm WARN locking path: 'C:\\a\\1\\b\\_locks\\ansi-styles-cedcc1e1e4774cd0.lock.STALE.STALE.STALE' }
npm ERR! Windows_NT 6.3.9600
npm ERR! argv "C:\\Program Files\\nodejs\\\\node.exe" "C:\\Program Files\\nodejs\\node_modules\\npm\\bin\\npm-cli.js" "install" "--dev" "--cache" "C:\\a\\1\\b"
npm ERR! node v0.12.7
npm ERR! npm v2.11.3
npm ERR! Attempt to unlock C:\a\1\s\com.example.web\node_modules\gulp-imagemin\node_modules\imagemin-pngquant\node_modules\pngquant-bin\node_modules\compare-size\node_modules\ava\node_modules\chalk\node_modules\ansi-styles, which hasn't been locked
npm ERR!
npm ERR! If you need help, you may report this error at:
npm ERR! <https://github.com/npm/npm/issues>
npm WARN locking Error: EMFILE, open 'C:\a\1\b\_locks\has-ansi-819c7cca16ab7ac8.lock.STALE.STALE.STALE'
npm WARN locking at Error (native)
2016-03-30T14:15:17.5709240Z npm WARN locking C:\a\1\b\_locks\has-ansi-819c7cca16ab7ac8.lock failed { [Error: EMFILE, open 'C:\a\1\b\_locks\has-ansi-819c7cca16ab7ac8.lock.STALE.STALE.STALE']

Answer 1

Re-installing NPM solved my issue:
npm install npm -g
Specifically, I added the circled task to my build: