How to fix uncompilable source code in NetBeans | Linux Mint

In this video I showed how to get rid of the error "uncompilable source code". The error - Exception in thread "main" java.lang.RuntimeException: Uncompilable source code - Null ctor sym type: RuntimeException(java.lang.String) Music used in this video - 🎵 Track Info: Title: First Light by Atch Genre and Mood: Dance & Electronic + Calm First Light - Atch https://soundcloud.com/atch-music Creative Commons — Attribution 3.0 Unported — CC BY 3.0 Free Download / Stream: http://bit.ly/-first-light Music promoted by Audio Library https://youtu.be/0SVbJldc5wM