Meteor (and probably Node) issues after updating from 1.1 to 1.4 (and back)

Prelude (skip to "Actual Problem" if you feel like it):

So I started building an app with a friend about a year and a half ago (Version "METEOR@1.1.0.3"). Both of us got new jobs and didn't really have much time to continue working on our app, which is why we put the operation on hold. In a technical sense, I was more of the muscles where my buddy was the brains of the operation. I was fine building templates and doing some styling and database operations, but most of the more advanced stuff was just a little bit out of my reach (keep in mind that at that point I only had like 2 months of experience with html, css, javascript, meteor, ios - overall just a lot to take in).

Anyhow, fast forward to today. I find myself having some time and trying to get back on the saddle. I read up on where meteor is today and realized a lot has happened since I last used it. Since I had to start from scratch anyway (because my knowledge is rusty), I decided to get some exposure to React and went through a few tutorials (including Wes Bos'). Initially I had trouble to get react running because there was some version conflict with node and npm I think. I did some unistalling and reinstalling, deleting (node) files and some linking (frankly, I have very little idea of what I actually did there). But in the end it worked.

Now my idea to is to refactor the old app to meteor + react. But for that I would very much need the old app to be running as it is really hard to get the dataflow just from the source code (couple of thousand lines)

Actual Problem:

I want to run a meteor application I built based on old version of meteor (1.1.0.3). I have since upgraded Meteor (at one point) and upgraded node and npm. One of the upgrades (my best guess) has messed with some files and packages and now I can not meteor run the app, as it crashes when doing so (even after downgrading to 1.1.0.3 again). Feel free to ask questions or for me to provide additional data (preferably with instructions for how to get the data - as I am a novice). Find below the error message and the git status of the app folder.

Error message when trying to meteor run:

While building the application:
node_modules/fbjs/flow/lib/dev.js:10:9: Unexpected token var
node_modules/loose-envify/cli.js:1:15: Unexpected token ILLEGAL
node_modules/ua-parser-js/dist/ua-parser.html:1: bad formatting in HTML template

Git status of app folder:

Changes not staged for commit:
(use "git add ..." to update what will be committed)
(use "git checkout -- ..." to discard changes in working directory)

modified:   packages
modified:   versions
Untracked files:
(use "git add ..." to include in what will be committed)

../node_modules/
no changes added to commit (use "git add" and/or "git commit -a")

Any help would be very much appreciated.

via Fabian Bosler