NPM Cache Config fails on second run

[oobles]

plugins {
id "com.moowork.node" version "1.3.1"
}
task npmCacheConfig(type: NpmTask) {
description = "Configure the NPM cache"
def npmCacheDir = "${gradle.getGradleUserHomeDir()}/caches/npm/"
outputs.files file(npmCacheDir)
args = ['config', 'set', 'cache', npmCacheDir]
}

When using a npmCacheConfig task like above using Gradle 5.5.1 we get the following error on the second run. The first run successfully creates and uses the directory, however, the second run fails.

• What went wrong:
  A problem was found with the configuration of task ':some-project:npmCacheConfig'.

Cannot write to file '/.../caches/npm' specified for property '$1' as it is a directory.

Is there a different method that should be used for configuring the NPM cache?

[deepy]

Shouldn't that be outputs.dir rather than outputs.files?

[oobles]

Yes. That was it! Thanks, was staring at it all day and knew it should be something simple.