(GH-51) Add handling of errors when loading classes

Previously if there was an error while parsing classes, it would cascade the
error and crash the sidecar.  This commit catches the error and gracefully
continues.

lib/puppet-languageserver-sidecar/puppet_helper.rb

@@ -47,8 +47,12 @@ def self.retrieve_classes(cache, options = {})
       classes = PuppetLanguageServer::Sidecar::Protocol::PuppetClassList.new
       manifest_path_list.each do |manifest_path|
         Dir.glob("#{manifest_path}/**/*.pp").each do |manifest_file|
-          if path_has_child?(options[:root_path], manifest_file)
-            classes.concat(load_classes_from_manifest(cache, manifest_file))
+          begin
+            if path_has_child?(options[:root_path], manifest_file)
+              classes.concat(load_classes_from_manifest(cache, manifest_file))
+            end
+          rescue StandardError => err
+            PuppetLanguageServerSidecar.log_message(:error, "[PuppetHelper::retrieve_classes] Error loading manifest #{manifest_file}: #{err} #{err.backtrace}")
           end
         end
       end
@@ -176,7 +180,6 @@ def self.load_classes_from_manifest(cache, manifest_file)
       end
 
       file_content = File.open(manifest_file, 'r:UTF-8') { |f| f.read }
-
       parser = Puppet::Pops::Parser::Parser.new
       result = nil
       begin