Rework exception handling

This commit gives the user a better output message:
- it uses the exception message if available or fallback on the "Error during update" message
- it prefixes the message by the current module name

This commits introduces a ModuleSync::Error that will be used to raise
exceptions, with a message outputed on stderr, but without a full
backtrace, useless for user.

It keeps the current behavior when error (ie. StandardError) comes from
templates (ie. ERB) rendering as user may need to see why the rendering
failed.

Git::GitExecuteError backtraces are now hidden too: user needs
to understand what happends, with the error message, but not where error
occured.

lib/modulesync.rb

@@ -12,6 +12,8 @@
 require 'monkey_patches'
 
 module ModuleSync # rubocop:disable Metrics/ModuleLength
+  class Error < StandardError; end
+
   include Constants
 
   def self.config_defaults
@@ -98,8 +100,8 @@ def self.manage_file(puppet_module, filename, settings, options)
         }
         template = Renderer.render(erb, configs, metadata)
         Renderer.sync(template, target_file)
-      rescue # rubocop:disable Lint/RescueWithoutErrorClass
-        $stderr.puts "Error while rendering #{filename}"
+      rescue StandardError => e
+        $stderr.puts "#{puppet_module.given_name}: Error while rendering file: '#{filename}'"
         raise
       end
     end
@@ -173,8 +175,14 @@ def self.update(cli_options)
     managed_modules.each do |puppet_module|
       begin
         manage_module(puppet_module, module_files, defaults)
-      rescue # rubocop:disable Lint/RescueWithoutErrorClass
-        warn "Error while updating '#{puppet_module.given_name}'"
+      rescue ModuleSync::Error, Git::GitExecuteError => e
+        message = e.message || "Error during '#{options[:command]}'"
+        message = "#{puppet_module.given_name}: #{message}"
+        $stderr.puts message
+        exit 1 unless options[:skip_broken]
+        errors = true
+        $stdout.puts "Skipping '#{puppet_module.given_name}' as update process failed"
+      rescue StandardError => e
         raise unless options[:skip_broken]
         errors = true
         $stdout.puts "Skipping '#{puppet_module.given_name}' as update process failed"

lib/modulesync/repository.rb

@@ -120,13 +120,10 @@ def submit_changes(files, options)
           repo.push('origin', branch, opts_push)
         end
       rescue Git::GitExecuteError => e
-        if e.message.match?(/working (directory|tree) clean/)
-          puts "There were no changes in '#{@directory}'. Not committing."
-          return false
-        else
-          puts e
-          raise
-        end
+        raise unless e.message.match?(/working (directory|tree) clean/)
+
+        puts "There were no changes in '#{@directory}'. Not committing."
+        return false
       end
 
       true