TracksLogWarn messages aren't shown in console in the client app

[jaclync]

Recently, we noticed a Tracks event wasn't actually tracked due to a validation error that wasn't logged anywhere in the console p1693362956666449/1692625489.705669-slack-C039133E1M3.

Automattic-Tracks-iOS/Sources/Event Logging/TracksEventService.m

Lines 59 to 61 in aad902b

	BOOL isValid = [tracksEvent validateObject:&error];
	if (!isValid) {
	TracksLogWarn(@"Error when validating TracksEvent: %@", error);

Upon inspection, TracksLoggingClass() is nil:

Automattic-Tracks-iOS/Sources/Model/ObjC/Common/TracksLogging.m

Lines 6 to 18 in aad902b

	static Class<TracksLoggingConfiguration> result = nil;
	static dispatch_once_t onceToken;
	dispatch_once(&onceToken, ^{
	#if SWIFT_PACKAGE
	Class loggingClass = NSClassFromString(@"AutomatticTracksModel.TracksLogging");
	#else
	Class loggingClass = NSClassFromString(@"TracksLogging");
	#endif
	if ([loggingClass conformsToProtocol: @protocol(TracksLoggingConfiguration)]) {
	result = loggingClass;
	}
	});
	return result;

It'd be great to fix this so that we can detect any validation errors during development.