Swift 4.1 Regression: EXC_BAD_ACCESS for Optimized Builds in Xcode 9.3

// crashes when called on an optimized build (-O or -Osize) both on simulator and device
func crash() {
	let blah = ProblematicEnum.problematicCase.problematicMethod()
	NSLog("\(blah)")
}

enum ProblematicEnum {
	case first, second, problematicCase
	
	func problematicMethod() -> SomeClass {
		let someVariable: SomeClass
		
		switch self {
		case .first:
			someVariable = SomeClass()
		case .second:
			someVariable = SomeClass()
		case .problematicCase:
			someVariable = SomeClass(someParameter: NSObject())
			_ = NSObject().description
			return someVariable // EXC_BAD_ACCESS (simulator: EXC_I386_GPFLT, device: code=1)
		}
		
		let _ = [someVariable]
		return SomeClass(someParameter: NSObject())
	}
	
}

class SomeClass: NSObject {
	override init() {}
	init(someParameter: NSObject) {}
}