Summary: @public
This moves us from warnings on name collisions to errors. If the error happens in initialization it will fatal out.
However, if the error happens while working (after initialization) then I did my best to make it recoverable. The rational behind this is that if you're working and you're changing names, you may introduce a duplication while moving things around. It will suck if you have to restart the server every time you do that.
Reviewed By: @frantic
Differential Revision: D2493098
Summary: @public
Have a top-level debug namespace: `ReactNativePackager`
And add a couple of debugs in the transformer. This is ground work for adding a verbose option.
Reviewed By: @DmitrySoshnikov
Differential Revision: D2489960
Summary: @public
The issue of colliding haste modules have came up many times and have wasted countless engineering hours. This will start warning about it and will also start selecting modules at random so that people don't depend on undefined behavior.
Additionally, this surfaced an issue where with assets we may fatally throw if the directory doesn't exist. This is fixed by checking the existence of the directory before trying to match files in it.
Reviewed By: @jingc
Differential Revision: D2478480
