fix #46: check sort array index before using it for sorting

lib/sort.go

@@ -23,8 +23,8 @@ import (
 	"sort"
 	"strconv"
 
-	"github.com/araddon/dateparse"
 	"codeberg.org/scip/tablizer/cfg"
+	"github.com/araddon/dateparse"
 )
 
 func sortTable(conf cfg.Config, data *Tabdata) {
@@ -38,6 +38,12 @@ func sortTable(conf cfg.Config, data *Tabdata) {
 		return
 	}
 
+	for _, column := range conf.UseSortByColumn {
+		if column > len(data.headers) {
+			return
+		}
+	}
+
 	// actual sorting
 	sort.SliceStable(data.entries, func(i, j int) bool {
 		// holds the result of a sort of one column