Return chart loading errors for display

ee/app/controllers/concerns/insights_actions.rb

@@ -6,6 +6,9 @@ module InsightsActions
   included do
     before_action :check_insights_available!
     before_action :validate_params, only: [:query]
+
+    rescue_from Gitlab::Insights::Validators::ParamsValidator::ParamsValidatorError,
+      Gitlab::Insights::Finders::IssuableFinder::IssuableFinderError, with: :render_insights_chart_error
   end
 
   def show
@@ -69,4 +72,8 @@ def serializer(chart_type)
   def config_data
     insights_entity.insights_config
   end
+
+  def render_insights_chart_error(exception)
+    render json: { message: exception.message }, status: 422
+  end
 end