Environments:

• Prettier Version: 1.14.3
• Running Prettier via: CLI
• Runtime: Node.js v10.13.0
• Operating System: macOS 10.14.1

Steps to reproduce:

• Create a file at the root level of a project named Docker.json (contents: {})
• Run npx prettier --list-different '**/*.json' --loglevel debug

Expected behavior:
For Prettier to run properly.

Actual behavior:
Prettier returns an error with the following logs:

[debug] resolve config from 'Docker.json'
[debug] loaded options `{"useTabs":false,"tabWidth":"unset"}`
[error] Unable to expand glob patterns: **/*.json !**/node_modules/** !./node_modules/** !**/.{git,svn,hg}/** !./.{git,svn,hg}/**
[error] Invalid `"tabWidth"` value. Expected an integer, but received `null`.

What's odd is that the following files work: docker.json, Docke.json, Doccer.json. It appears somehow related to the Docker prefix. As far as I can tell, anything after Docker still causes an issue (I first noticed this on a Dockerrun.aws.json file).