usql updates

usql/csvreader.cpp

@@ -1,4 +1,6 @@
+#include <errno.h>
 
+#include "exception.h"
 #include "csvreader.h"
 #include "parser.h"
 
@@ -30,9 +32,10 @@ int CsvReader::parseCSV(const std::string &filename, std::vector<ColDefNode> &co
 	std::vector<std::string> line;
 	line.reserve(32);
 
+	errno = 0;
 	FILE* fp = fopen(filename.c_str(), "r");
 	if (fp == NULL)
-	    exit(EXIT_FAILURE);
+		throw Exception("load from csv, cannot read from file(" + std::to_string(errno) + ")");
 
 	char* line_str = NULL;
 	size_t len = 0;