feat: final firsts initialization

src/parser/grammar_basic.c

@@ -160,13 +160,15 @@ struct ast *parse_command(struct lexer_context *ctx)
     }
     else if (is_first(*token, RULE_SHELL_COMMAND))
     {
-        parse_shell_command(ctx);
+        result = parse_shell_command(ctx);
     }
     else
     {
         perror("Syntax error: unexpected token");
         return NULL;
     }
+
+    return result;
 }
 
 /* @brief: frees command_elements and redirections lists (helper func)