fix: correctly escape output stream buffer for models getters

src/baseexpression.cpp

@@ -44,6 +44,10 @@ namespace morm
 
 BaseExpression::BaseExpression()
 {
+	/*
+	 * may it would be better for the ModelConnector/JSONConnector/PostgreSQLConnector to provide one scratch buffer?
+	 */
+	scratch_buffer = &scratch_buffer_local;
 	clear();
 }