Fix error, submission, hints and help views

app/models/code_ocean/error.rb

@@ -0,0 +1,19 @@
+module CodeOcean
+  class Error < ApplicationRecord
+    belongs_to :execution_environment
+
+    scope :for_execution_environment, ->(execution_environment) { where(execution_environment_id: execution_environment.id) }
+    scope :grouped_by_message, -> { select('MAX(created_at) AS created_at, MAX(id) AS id, message, COUNT(id) AS count').group(:message).order('count DESC') }
+
+    validates :execution_environment_id, presence: true
+    validates :message, presence: true
+
+    def self.nested_resource?
+      true
+    end
+
+    def to_s
+      id.to_s
+    end
+  end
+end