#113 making requested changes

Author: SingingBush

source/mysql/logger.d

@@ -42,7 +42,7 @@ version(Have_vibe_core) {
 	alias logError = std.experimental.logger.errorf;
 	alias logCritical = std.experimental.logger.criticalf;
 	//alias logFatal = std.experimental.logger.fatalf;
-}
+} else static assert(false);
 
 unittest {
 	version(Have_vibe_core) {

source/mysql/protocol/comms.d

@@ -534,7 +534,9 @@ package(mysql) bool execQueryImpl(Connection conn, ExecQueryImplInfo info, out u
 		conn.resetPacket();
 		auto okp = OKErrorPacket(packet);
 
-		logError("packet error: %s %s", okp.error, okp.message);
+		if(okp.error) {
+			logError("packet error: %s", cast(string) okp.message);
+		}
 
 		enforcePacketOK(okp);
 		ra = okp.affected;