Resolve "Cater for errors being nil and update checks for retryable errors"

Related to #34

errors/errors.go

@@ -102,9 +102,15 @@ func HTTPCodeOnly(code int) error {
 }
 
 func HTTPWithError(code int, err error) error {
+	var errorMessage string
+	// This check is here just as a failsafe to seg faults, if err is nil then just return assign an empty string as message.
+	if err != nil {
+		errorMessage = err.Error()
+	}
+
 	wrappedErr := &CustomError{
 		code:    code,
-		message: err.Error(),
+		message: errorMessage,
 		caller:  GetCaller(2),
 		cause:   err,
 	}