Trying to install an invalid extension file gives "Unknown internal error" message

[gruehle]

Steps to repro:

1. Try to install a file that is not a valid extension. For example:
   https://github.com/adobe/brackets/blob/master/src/styles/images/active_back.png

Results
Error dialog that says: "Installation failed. Unknown internal error."

Expected
A more helpful error message :-)

[gruehle]

This same error occurs if you try to install a valid .zip file that does not contain a valid extension.

[peterflynn]

FBNC @gruehle -- pull #3178 included a fix for this (without realizing it -- I'd thought this bug was a different case of errors not getting bubbled up to the UI properly)

[gruehle]

@dangoor @peterflynn - Well, the error is better now, but still not great.

Trying to install "https://dl.dropbox.com/u/17644987/README.md" gives the error: "/var/folders/6z/3_mbdyv124xbql2flrtwj5lh0000gn/T//brackets.download1 is not a valid zip file."

The "is not a valid zip file" part is good, but the filename is pretty scary looking :-)

[gruehle]

Removing the FBNC label. I don't think this is a sprint-stopper, but I'll keep the Sprint 22 milestone on for now.

[peterflynn]

Hmm, yeah... showing the exact local filename made more sense back when we were downloading to the parent of the extensions folder. But even then I think it wasn't that useful in the final production code because we delete the file the instant the error message is shown. I'll put up a pull to just not show filenames in cases like this.

[njx]

FBNC (again) to @gruehle

[gruehle]

Much better error messages. Thanks! Closing.