fix #26: check db file existence before trying to read from it

cmd/crud.go

@@ -107,6 +107,10 @@ func Get(conf *cfg.Config) *cobra.Command {
 				attr.Key = args[0]
 			}
 
+			if err := conf.DB.Exists(); err != nil {
+				return err
+			}
+
 			entry, err := conf.DB.Get(&attr)
 			if err != nil {
 				return err
@@ -207,6 +211,10 @@ func List(conf *cfg.Config) *cobra.Command {
 				conf.Mode = "wide"
 			}
 
+			if err := conf.DB.Exists(); err != nil {
+				return err
+			}
+
 			entries, err := conf.DB.List(&attr, conf.Fulltext)
 			if err != nil {
 				return err