Why am I getting Unexpected token '\\u0000'

This is probably a Windows specific issue but I haven't found any information when googling this issue. I had been using ionic framework which relies on Cordova (or Phonegap). However, the problem is not specific to any of these packages. I see this error quite often. So, the error is when I run a command such as the following:

npm install -g cordova

However, I could substitute various other packages and get the same error. I'll paste the snippet (very brief) below of the error message. What is strange is that I had an ionic project working in that directory earlier. Then today it told me that ionic could not be found. My hunch is that this is a different issue than the main issue I am describing here.

I installed git bash so I do have a linux-like environment that I could try. I would just select Git Bash for a bash window with various bash commands. If there is an easier way to fix this for Windows users, please let me know. I have seen courses on Pluralsight where the instructors seem to be happily using npm with no problems. Also, when I use yeoman, I also at some point, in many cases, get the same error.
The error is

npm ERR! Failed to parse json
npm Unexpected token '\u0000' at 1:1
npm ERR!
npm ERR! ^
npm ERR! File: c:\Users\Bruce\AppData\Roaming\npm-cache\amdefine\1.0.0\package\package.json
npm ERR! Failed to parse package.json data.
npm ERR! package.json must be actual JSON, not just JavaScript.
npm ERR!
npm ERR! This is not a bug in npm
npm ERR! Tell the package author to fix their package.json file. JSON.parse.

Thanks in advance for any help/advice, Bruce

Via this question on SO it could be that you just have to do:

npm cache clean.

But, also try the other methods suggested there like adding the registry option:

npm install <packagename> --registry http://registry.npmjs.org/.

Or, if you've been mingling with the package.json file by yourself, check if it's valid.