The errors that I got are all related to trying to use fonts that are not available on my system. You can use printArray(PFont.list()); to find the font list for your system. Then you will have to find/replace all the unavailable fonts in your source code to use fonts which are available on your system. There is an Examples/meter/Change_Fonts demo which might be helpful; it runs on my Mac without changing any of the fonts in the meter library, so in theory all you have to do is change the fonts in your source code. However, this alone won’t make the error message go away. You also forgot to set the serial_port; need to use something like this:
serial_port = new Serial(this, Serial.list()[2], 9600);
Then your demo should run.
