The only error is the version field. There are also some warnings for fields that should be in the file (keywords, bugs, licenses, author, contributors, and repository fields), as well as recommendations for having a homepage and engines fields (which are optional).
Here are the results of the package.json validator for the package.json file in this repository:
The only error is the version field. There are also some warnings for fields that should be in the file (keywords, bugs, licenses, author, contributors, and repository fields), as well as recommendations for having a homepage and engines fields (which are optional).