npx frontity create-package causes error in npm 7

[mburridge]

Bug report

• I've updated both my project and my packages to the latest Frontity versions: https://docs.frontity.org/guides/keep-frontity-updated
• I've searched for existing issues.
• I've checked the documentation: https://docs.frontity.org
• I've checked the community forum: https://community.frontity.org

Expected behavior

No error should occur, create-package should behave the same as it does in earlier versions of npm.

Observed behavior

Steps involved to reproduce the problem

Upgrade npm to v7 and run npx frontity create-package.

Info about your system

System:

• OS: macOS 11.2
• CPU: (8) x64 Intel(R) Core(TM) i5-8259U CPU @ 2.30GHz
• Memory: 338.60 MB / 16.00 GB
• Shell: 5.8 - /bin/zsh

Binaries:

• Node: 12.19.0 - ~/.nvm/versions/node/v12.19.0/bin/node
• npm: 6.14.11 - ~/.nvm/versions/node/v12.19.0/bin/npm

Browsers:

• Chrome: 88.0.4324.146
• Edge: Not Found
• Firefox: 84.0.2
• Safari: 14.0.3

npmPackages:

• @frontity/core: ^1.10.1 => 1.10.1
• @frontity/html2react: ^1.6.1 => 1.6.1
• @frontity/mars-theme: ./packages/mars-theme => 1.5.0
• @frontity/tiny-router: ^1.3.2 => 1.3.2
• @frontity/wp-source: ^1.11.1 => 1.11.1
• frontity: ^1.14.1 => 1.14.1
• my-first-theme: file:packages/my-first-theme => 1.0.0

npmGlobalPackages:

• frontity: Not Found
• npx: Not Found

Possible solution