It may be that everybody knows this already or that the editors you are using already do this but I will share anyway.
Writing the shaders for the fur material gave me plenty of problems as I usually use console.log to get to the bottom of the silly mistakes I make when writing code (and have just discovered the debugger and breakpoints in the FF development tools - more to learn yet). Then RaananW and jerome pointed me in the direction of shader editors in the Chrome and FF browsers. However Visual Studio Code nor FF showed me where the syntax errors were in the shader code. Then I came across http://shdr.bkcore.com/ which helped to find those silly errors in the syntax.
For me it saved my sanity.