More detail to JSON.parse() error in Socket.prototype.recvJSON

This is likely the cause of the vauge logged error that I and other
sysops see from time to time:
srvc 0000 JSON SyntaxError: JSON.parse

... so log the function name and the contents of the string that's
failing to parse.

exec/load/json-sock.js

@@ -45,7 +45,7 @@ Socket.prototype.recvJSON = function() {
 			}
 		} 
 		catch(e) {
-			log(LOG_ERROR,e);
+			log(LOG_ERROR,'recvJSON(): ' + e + format(" '%s'", packet));
 		}
 	}
 	return packet;