Error if added Content-Type

[amian84]

This issue pertains to the following package(s):

• [ ] GraphQL Playground - Electron App
• [ ] GraphQL Playground HTML
• [ ] GraphQL Playground
• [x] GraphQL Playground Express Middleware
• [ ] GraphQL Playground Hapi Middleware
• [ ] GraphQL Playground Koa Middleware
• [ ] GraphQL Playground Lambda Middleware

What OS and OS version are you experiencing the issue(s) on?

Ubuntu 18.04

What version of graphql-playground(-electron/-middleware) are you experiencing the issue(s) on?

1.7.20

What is the expected behavior?

Added header content-type if you write a content-type in header

What is the actual behavior?

if you try add header "Content-type", doesnt works, playground concat application/json with the new content-type setted. Only works properly if write content-type key in lowercase

What steps may we take to reproduce the behavior?

Added header Content-Type (not in lowecase) to headers

[homerjam]

Please fix this! :)

It also happens with the Accept header and means that the playground can't be used with the Shopify Storefront API.

Edit:

Only works properly if write content-type key in lowercase

Just saw this workaround!