Add helpful invalid gemspec error message for bundle install --standalone

[RochesterinNYC]

• when a gem/dependency has an invalid gemspec
• addresses Bundle install with bundler 1.11.x errors with "no implicit conversion of Array into String" #4275

Output whould now be:

$ bundle install --standalone
Using mono_logger 1.1.0
Using multi_json 1.11.2
Using rack 1.6.4
Using redis 3.2.2
Using tilt 2.0.2
Using thread_safe 0.3.5
Using bundler 1.12.0.pre
Using rack-protection 1.5.3
Using vegas 0.1.11
Using redis-namespace 1.5.2
Using tzinfo 1.2.2
Using sinatra 1.4.7
Using rufus-scheduler 2.0.24
Using resque 1.24.1
Using resque-scheduler 2.2.0
You have one or more invalid gemspecs that need to be fixed.
resque-scheduler 2.2.0 has an invalid gemspec

[segiddins]

I would extract out getting spec.require_paths and handle the exception there?

[RochesterinNYC]

gem_path is where the exception is occurring, but I see your point regarding moving the exception handling down a level/method call.

[indirect]

Thanks!

[segiddins]

@indirect homu, please