General Dynamics Ordnance and Tactical Systems interview questions

I applied online for Saco, Maine. Received a call from the HR to schedule an interview with the hiring manager after few days of my application. The interview with the hiring manager was a 30 mins call over the phone. The interview went well and the hiring manager praised my experience and skills and that i wont need training when if I start this position. Hiring manager told me that a second person interview will be scheduled once the supervisor comes back in office and that would be in one week. Three weeks passed by and I never heard from her or HR. They ghosted me. I reached out to HR and they never replied me. I reached out to hiring manager and she informed me that the position hasn't been filed and HR should have contacted me to loop me back in, which got me confused. I didn't hear from HR until I decided to call. HR informed me that position has been already filled. The hiring manager didn't that the position has been filled?? They apparently had no real job and this was just a terrible ghosting experience