fix: ensure that no index out of bounds read can happen when populating node modules

[makepanic]

fixes #289

[makepanic]

@viktoria-shirunova can you check if this fixes your issue? I couldn't reproduce it locally but from the stacktrace it seems like the issue was the access to index 0 when its size was 0.
We're now trying to be more graceful. I'm not sure if a selection model of null works though.

[viktoria-shirunova]

@makepanic I'm sorry, but still the version 2019.3.1-0 is published where the exception is reproduced and, unfortunately, I don't know how where from to take the plugin other way. For reproducing - you need to be sure that no node.js is installed on your computer. If any node.js is installed - no exception then.

[makepanic]

I've tried to uninstall node.

The intellij node picker widget has a graceful fallback for me:

The stacktrace pointed to an issue where the module picker had no modules to pick from.
We removed the nullpointer exception but I can't get this to happen locally.