Allow `undefined` Header Value

Added

• Allow undefined as a header input value

Strip Class Symbols

Fixed

• Strips symbols from the class, in addition to the previous exports

Abort Before Started

Fixed

• Set aborted = true internally when started == false since nothing will be listening yet

Allow `abort` after `req.finished`

Fixed

• Previously impossible to abort response part-way because abort() blocked when req.finished = true
• The abort event will only trigger once from now on

Added

• Add new req.closed to indicate the current request/response stream has closed

Configure headers on `createBody`

Added

• Add optional options with support for headers to createBody

Trailer Support

Changed

• Add support for trailer as Promise<Headers>
• Rename getHeaders() to allHeaders
• Using symbols for private properties

Added

• Support Headers#clone(), Body#clone(), Request#clone() and Response#clone()
• Add Headers#clear()

Allow `undefined` in `CreateBody`

Fixed

• Explicitly define undefined in CreateBody union types

Export `CreateBody` Type

Changed

• Export CreateBody supported types for universal body

Fix `Headers#asObject` Return Type

Fixed

• Use stricter object definition for asObject to support { [key: string]: string }

Default Request Method

Changed

• Default Request#method to GET so it's always a string