Handle failure to install local library in CI script

Author: ianfixes

CHANGELOG.md

@@ -23,6 +23,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 - Library installation no longer "fails" if the library is already installed
 - Platform definition for `mega2560` now includes proper AVR compiler flag
 - `CppLibrary::vendor_bundle?` now asks where gems are, instead of assuming `vendor/bundle/`
+- `install_local_library` step in `arduino_ci_remote.rb` now properly surfaces any error message
 
 ### Security
 

exe/arduino_ci_remote.rb

@@ -248,17 +248,22 @@ def perform_compilation_tests(config)
   installed_library_path = attempt("Installing library under test") do
     @arduino_cmd.install_local_library(Pathname.new("."))
   end
-  if installed_library_path.exist?
+
+  if !installed_library_path.nil? && installed_library_path.exist?
     inform("Library installed at") { installed_library_path.to_s }
   else
     assure_multiline("Library installed successfully") do
-      # print out the contents of the deepest directory we actually find
-      @arduino_cmd.lib_dir.ascend do |path_part|
-        next unless path_part.exist?
-
-        break display_files(path_part)
+      if installed_library_path.nil?
+        puts @arduino_cmd.last_msg
+      else
+        # print out the contents of the deepest directory we actually find
+        @arduino_cmd.lib_dir.ascend do |path_part|
+          next unless path_part.exist?
+
+          break display_files(path_part)
+        end
+        false
       end
-      false
     end
   end
   library_examples = @arduino_cmd.library_examples(installed_library_path)