To make mistakes when playing solo guitar music is of course very common, and to be able to play a piece without making mistakes takes a lot of practice. First of all, I'd try not to be too critical of my own playing when I practice. You don't necessarily want to label the "mistakes" as mistakes! :) Just see the mistakes as a necessary thing that happens when you practice. When you're performing a song for an audience, know that everyone is on YOUR side, and everyone wants you to do good. Even if you make a mistake, that is OK too.
There are no shortcuts - it's all about playing the song over and over - hundreds of times. When you practice the difficult sections in the song, you never waste any time. That time you put in to practicing just a short phrase or section of the song will help you in ALL your guitar playing. Technique, timing, accuracy.. everything!
Record yourself a lot and listen back. Then you really hear what you need to work on.
So glad you like the courses at ProGuitar! Thanks for being part of the community! :)