As a heads up to everyone, if you're using npm v6.x it won't work with Node 10.x, including for basic npm install. Glancing around online, it sounds like it may be supported later in the 10.x line. I ran into this problem after a Homebrew upgrade, so you might be doing updates a bit more under the hood.
To get around this, you'll have to downgrade node to the 9.x set of releases. There's a tool called NVM <https://github.com/creationix/nvm> that seems to work pretty decently, but I'm sure there are other alternatives, too. The PR to update angular <https://github.com/apache/metron/pull/1096/files#diff-e8f55f2d9e4f18085052a36d750e9648R28> uses node 9.11.1 and npm 5.8.0 for metron-alerts, so this seems like a reasonable recommendation to settle on for now.
