Unfortunately, Firefox and Safari still don't provide column numbers in error stack traces, only line numbers, which are next to useless if your code is minified. Here's the Firefox bug:
Not much discussion about fixing it :( This caused a lot of pain at my last job. When we got Chrome and IE10 stack traces, we had a script run them through our source maps and show us the exact, full stack trace through the unminified source. Firefox's and Safari's traces remained impenetrable, short of manually inspecting the minified line of code and guessing.
https://bugzilla.mozilla.org/show_bug.cgi?id=762556
Not much discussion about fixing it :( This caused a lot of pain at my last job. When we got Chrome and IE10 stack traces, we had a script run them through our source maps and show us the exact, full stack trace through the unminified source. Firefox's and Safari's traces remained impenetrable, short of manually inspecting the minified line of code and guessing.