Shared via Pony Playground (https://playground.ponylang.io/?gist=6f1868c2c7e6917be17cd437a0c34ca3)

main.pony

trait SomeTrait

	fun getVal() : U32 =>

		2

class SomeClass

class Some is SomeTrait

	// works, if ` = SomeClass` is uncommented:
	embed eClass : SomeClass // = SomeClass

	new create( env' : Env) =>

		// // works, if line below is uncommented:
		// eClass = SomeClass

		getVal()

		// doesnt work, if line below is uncommented:
		eClass = SomeClass

actor Main
	new create( e' : Env) =>
		e'