Debugging in a Rails environment

Hi, I’m a newbie about everything concerning frontend development, and I’m trying to build a little app in Elm using what I think are pretty common tools: webpack and foreman.
The problem is that my development cycle is terrible, I have literally no idea how to debug the code I write and right now I’m just starting foreman and hoping that the compiler doesn’t complain, and if it doesn’t complain… well I’m in troubles, I’m looking at a blank page right now.
In general I’m not sure I know what I’m doing and what steps should I take when I have a problem, http://debug.elm-lang.org doesn’t help me much honestly because I have the thing running on my computer and it doesn’t feel very productive to cut and paste it every time on internet.
Right now for example my code compiles and then

TypeError: undefined is not an object (evaluating ‘__WEBPACK_IMPORTED_MODULE_0__Annotator_Main___default.a.Annotator.Main’)

and I’m stuck.
Any suggestions? I’ve read around Elm has great debugging tools, but I don’t know how to use them…

ngw

That link is outdated and refers to historical debug support, rather than current debug support. What version of Elm are you using? I’m not familiar with the webpacker, but it sounds like debug mode should be enabled by default.

0.18
I think it’s enabled by default! This is what I see on my console:

16:27:41 webpack.1 |  10% building modules 0/1 modules 1 active ...ill/app/javascript/Annotator/Main.elmStarted compiling Elm..
16:27:41 webpack.1 | Running /Users/ngw/quill/node_modules/.bin/elm-make /Users/ngw/quill/app/javascript/Annotator/Main.elm --yes --warn --debug --output /var/folders/qw/znqb2fcs5d58r4h4z8lxbhqc0000gn/T/1171120-3000-gttcwt.le6al.js
16:27:42 webpack.1 | Success! Compiled 1 module.

I just don’t know what to do with this --debug.