Return 406 instead of 500 for statistics.json

Fixes #7406

app/controllers/node_info_controller.rb

@@ -13,6 +13,9 @@ class NodeInfoController < ApplicationController
   end
 
   def statistics
-    @statistics = NodeInfoPresenter.new("1.0")
+    respond_to do |format|
+      format.json { head :not_acceptable }
+      format.all { @statistics = NodeInfoPresenter.new("1.0") }
+    end
   end
 end

spec/controllers/node_info_controller_spec.rb

@@ -51,6 +51,11 @@ describe NodeInfoController do
   end
 
   describe "#statistics" do
+    it "returns a 406 for json format" do
+      get :statistics, format: "json"
+      expect(response.code).to eq("406")
+    end
+
     it "responds to html" do
       get :statistics, format: "html"
       expect(response.code).to eq("200")