Fix var underscores

src-tauri/yaak-templates/src/parser.rs

@@ -271,7 +271,7 @@ impl Parser {
             let is_valid = if start_pos == self.pos {
                 ch.is_alphabetic() // First char has to be alphabetic
             } else {
-                ch.is_alphanumeric() || ch == '-' || ch == '-'
+                ch.is_alphanumeric() || ch == '-' || ch == '_'
             };
             if is_valid {
                 text.push(ch);
@@ -441,6 +441,20 @@ mod tests {
         );
     }
 
+    #[test]
+    fn var_underscores() {
+        let mut p = Parser::new("${[ a_b ]}");
+        assert_eq!(
+            p.parse().tokens,
+            vec![
+                Token::Tag {
+                    val: Val::Var { name: "a_b".into() }
+                },
+                Token::Eof
+            ]
+        );
+    }
+
     #[test]
     fn var_prefixes() {
         let mut p = Parser::new("${[ -a ]}${[ _a ]}${[ 0a ]}");