Namespace changes in React\Promise v3.x

[whoisninjaturtle]

React\Promise reorganized their project structure in version 3, such that the RejectedPromise class once located in the React\Promise namespace is now located in React\Promise\Internal instead.

This causes a missing class inside Ratchet\Pawl\Connector which still attempts to import it from the React\Promise namespace.

The composer.json dependency for React\Promise is created by React\Socket which requires ^3.2 || ^2.6 || ^1.2.1 but neither React\Socket nor Ratchet\Pawl specify a major version below 3, meaning the default dependencies lead you into this situation.

In either case, it seems to go hand in hand; the namespace can neither be adjusted nor left alone without revisiting those dependencies in one direction or the other.

[clue]

The RejectedPromise class should not be used explicitly and should be replaced with a reject() function call instead, see reactphp/promise#155 / reactphp/promise#164 / reactphp/promise#165.