crash in scan.rb - no implicit conversion of nil into Array

[battlmonstr]

New Issue Checklist

• [ x ] Updated fastlane to the latest version
• [ x ] I have read the Contribution Guidelines

Issue Description

Complete output when running fastlane, including the stack trace and command used

You can use: --capture_output as the last commandline argument to get that collected for you

$ fastlane all
[16:02:06]: ------------------
[16:02:06]: --- Step: scan ---
[16:02:06]: ------------------
[16:02:06]: $ xcodebuild -list -workspace xxx.xcworkspace
[16:02:16]: Command timed out after 10 seconds on try 1 of 4, trying again...
[16:02:26]: Command timed out after 10 seconds on try 2 of 4, trying again...
[16:02:36]: Command timed out after 10 seconds on try 3 of 4, trying again...
[16:02:46]: Command timed out after 10 seconds on try 4 of 4
+------------------------+-------------------+
|                Lane Context                |
+------------------------+-------------------+
| DEFAULT_PLATFORM       | ios               |
| PLATFORM_NAME          | ios               |
| LANE_NAME              | ios all           |
| SCAN_DERIVED_DATA_PATH | build/DerivedData |
+------------------------+-------------------+
[16:02:46]: no implicit conversion of nil into Array
[16:02:47]: fastlane finished with errors
.../fastlane/lib/fastlane/actions/scan.rb:32:in `-': [!] no implicit conversion of nil into Array (TypeError)
	from .../fastlane/lib/fastlane/actions/scan.rb:32:in `ensure in run'
	from .../fastlane/lib/fastlane/actions/scan.rb:34:in `run'
	from .../fastlane/lib/fastlane/runner.rb:243:in `block (2 levels) in execute_action'
	from .../fastlane/lib/fastlane/actions/actions_helper.rb:50:in `execute_action'
	from .../fastlane/lib/fastlane/runner.rb:221:in `block in execute_action'
	from .../fastlane/lib/fastlane/runner.rb:217:in `chdir'
	from .../fastlane/lib/fastlane/runner.rb:217:in `execute_action'
	from .../fastlane/lib/fastlane/runner.rb:139:in `trigger_action_by_name'
	from .../fastlane/lib/fastlane/fast_file.rb:146:in `method_missing'
	from Fastfile:9:in `block (2 levels) in parsing_binding'
	from .../fastlane/lib/fastlane/lane.rb:33:in `call'
	from .../fastlane/lib/fastlane/lane.rb:33:in `call'
	from .../fastlane/lib/fastlane/runner.rb:192:in `try_switch_to_lane'
	from .../fastlane/lib/fastlane/fast_file.rb:282:in `test'
	from Fastfile:51:in `block (2 levels) in parsing_binding'
	from .../fastlane/lib/fastlane/lane.rb:33:in `call'
	from .../fastlane/lib/fastlane/lane.rb:33:in `call'
	from .../fastlane/lib/fastlane/runner.rb:49:in `block in execute'
	from .../fastlane/lib/fastlane/runner.rb:45:in `chdir'
	from .../fastlane/lib/fastlane/runner.rb:45:in `execute'
	from .../fastlane/lib/fastlane/lane_manager.rb:52:in `cruise_lane'
	from .../fastlane/lib/fastlane/command_line_handler.rb:30:in `handle'
	from .../fastlane/lib/fastlane/commands_generator.rb:105:in `block (2 levels) in run'
	from .../vendor/bundle/ruby/2.0.0/gems/commander-4.4.3/lib/commander/command.rb:178:in `call'
	from .../vendor/bundle/ruby/2.0.0/gems/commander-4.4.3/lib/commander/command.rb:178:in `call'
	from .../vendor/bundle/ruby/2.0.0/gems/commander-4.4.3/lib/commander/command.rb:153:in `run'
	from .../vendor/bundle/ruby/2.0.0/gems/commander-4.4.3/lib/commander/runner.rb:446:in `run_active_command'
	from .../fastlane_core/lib/fastlane_core/ui/fastlane_runner.rb:38:in `run!'
	from .../vendor/bundle/ruby/2.0.0/gems/commander-4.4.3/lib/commander/delegates.rb:15:in `run!'
	from .../fastlane/lib/fastlane/commands_generator.rb:302:in `run'
	from .../fastlane/lib/fastlane/commands_generator.rb:42:in `start'
	from .../fastlane/lib/fastlane/cli_tools_distributor.rb:65:in `take_off'
	from .../bin/fastlane:15:in `<top (required)>'
	from .../ruby-2.0.0-p648/bin/fastlane:23:in `load'
	from .../ruby-2.0.0-p648/bin/fastlane:23:in `<main>'
	from .../ruby-2.0.0-p648/bin/ruby_executable_hooks:15:in `eval'
	from .../ruby-2.0.0-p648/bin/ruby_executable_hooks:15:in `<main>'

Environment

Please run fastlane env and copy the output below. This will help us help you 👍
If you used --capture_output option please remove this block - as it is already included there.

### Stack

| Key                 | Value                                       |
| ------------------- | ------------------------------------------- |
| OS                  | 10.11.6                                     |
| Ruby                | 2.0.0                                       |
| Bundler?            | true                                        |
| Git                 | git version 2.10.0                          |
| Installation Source | ~/.rvm/gems/ruby-2.0.0-p648/bin/fastlane    |
| Host                | Mac OS X 10.11.6 (15G1004)                  |
| Ruby Lib Dir        | ~/.rvm/rubies/ruby-2.0.0-p648/lib           |
| OpenSSL Version     | OpenSSL 1.0.2h  3 May 2016                  |
| Is contained        | false                                       |
| Is homebrew         | false                                       |
| Xcode Path          | /Applications/Xcode.app/Contents/Developer/ |
| Xcode Version       | 8.0                                         |

### fastlane gems

| Gem      | Version | Update-Status      |
| -------- | ------- | ------------------ |
| fastlane | 2.19.1  |   Update available |

[fastlane-bot]

It seems like you have not included the output of fastlane env

To make it easier for us help you resolve this issue, please update the issue to include the output of fastlane env 👍

[mfurtak]

Thanks for the fix in #8678 🚀