Haxe / PHP server changing output without compiling file

Question

I'm making a web app in Haxe and compiling it to PHP. I test the PHP code on my local server (php -S).

Here's the code:

    //...
    switch(page) {
        //...
        case "user":
            //if logged in, display profile; if not, redirect to login

            var loggedIn = false;

            //check if user is logged in
            if (Session.exists("username") && Session.exists("password")) {
                var username:String = Session.get("username");
                var password:String = Session.get("password");

                //check the password
                var conn = Mysql.connect({user: "..." pass: "...", host: "127.0.0.1", database: "..."});
                var dbpass = conn.request("SELECT password FROM users WHERE username = \'" + username + "\';").results().first().password;

                if (password == dbpass)
                    loggedIn = true;
            }

            if (!loggedIn) {
                returnPage += File.getContent("../html/login.html");
            } else {
                //TODO add profile page
            }
    }

The server gives this error (no error when compiling):

uncaught exception: Unable to call <exists>

in file: /.../lib/haxe/ds/StringMap.class.php line 31
#0 /.../lib/Open.class.php(9): haxe_ds_StringMap->__call('exists', Array)
#1 /.../open/index.php(11): Open::main()
#2 {main}

And this is where the really weird part begins: When I change something in the code (it doesn't have to affect the app, even a comment would do), don't build it and reload the page, it suddenly works. But when i build the code, it gives the error again.

Is it some bug in the server or do I make a mistake somewhere?

---

EDIT

I moved the testing server to Apache and the problem still persists.

Answer 1

I found out that the exists function from the StringMap class didn't get compiled to PHP for some reason, so i edited the code to be like this:

//...
if (Session.get("username") != null && Session.get("password") != null) {

and it works now. Don't know why the output changed when I didn't compile the file, but that doesn't matter.