Accurately track any JSON Parser errors

Provide the context of what JSON was received to Honeybadger and Raven

lib/react_on_rails.rb

@@ -3,6 +3,8 @@
 require "rails"
 
 require "react_on_rails/error"
+require "react_on_rails/prerender_error"
+require "react_on_rails/json_parse_error"
 require "react_on_rails/react_on_rails_helper"
 require "react_on_rails/controller"
 require "react_on_rails/version"

lib/react_on_rails/json_parse_error.rb

@@ -0,0 +1,26 @@
+module ReactOnRails
+  class JsonParseError < ::ReactOnRails::Error
+    attr_reader :json
+
+    def initialize(parse_error, json)
+      @json = json
+      @original_error = parse_error
+      super(parse_error.message)
+    end
+
+    def to_honeybadger_context
+      to_error_context
+    end
+
+    def raven_context
+      to_error_context
+    end
+
+    def to_error_context
+      {
+        original_error: @original_error,
+        json: @json
+      }
+    end
+  end
+end

lib/react_on_rails/prerender_error.rb

@@ -27,6 +27,21 @@ def raven_context
       to_error_context
     end
 
+    def to_error_context
+      result = {
+        component_name: component_name,
+        err: err,
+        props: props,
+        js_code: js_code,
+        console_messages: console_messages
+      }
+
+      if err.respond_to?(:to_error_context)
+        result.merge!(err.to_error_context)
+      end
+      result
+    end
+
     private
 
     def calc_message(component_name, console_messages, err, js_code, props)
@@ -60,14 +75,5 @@ def calc_message(component_name, console_messages, err, js_code, props)
       [backtrace, message]
     end
 
-    def to_error_context
-      {
-        component_name: component_name,
-        err: err,
-        props: props,
-        js_code: js_code,
-        console_messages: console_messages
-      }
-    end
   end
 end

lib/react_on_rails/server_rendering_pool/ruby_embedded_java_script.rb

@@ -48,7 +48,12 @@ def exec_server_render_js(js_code, render_options, js_evaluator = nil)
             @file_index += 1
           end
           json_string = js_evaluator.eval_js(js_code)
-          result = JSON.parse(json_string)
+          result = nil
+          begin
+            result = JSON.parse(json_string)
+          rescue JSON::ParserError => e
+            raise ReactOnRails::JsonParseError.new(e, json_string)
+          end
 
           if render_options.logging_on_server
             console_script = result["consoleReplayScript"]

spec/dummy/app/controllers/application_controller.rb

@@ -6,6 +6,8 @@ class ApplicationController < ActionController::Base
   protect_from_forgery with: :exception
 
   rescue_from ReactOnRails::PrerenderError do |err|
+    raise err if err.err.is_a?(ReactOnRails::JsonParseError)
+
     Rails.logger.error("Caught ReactOnRails::PrerenderError in ApplicationController error handler.")
     Rails.logger.error(err.message)
     Rails.logger.error(err.backtrace.join("\n"))

spec/dummy/spec/requests/server_render_check_spec.rb

@@ -13,6 +13,16 @@
       .to eq("Mr. Server Side Rendering")
   end
 
+  it "generates a prerender error if invalid JSON returned" do
+    invalid_json = "{ some invalid JSON"
+    allow(ReactOnRails::ServerRenderingPool::RubyEmbeddedJavaScript)
+      .to receive(:eval_js).and_return(invalid_json)
+    expect { get server_side_hello_world_with_options_path }.to(raise_error do |error|
+      expect(error.raven_context[:json]).to eq(invalid_json)
+      expect(error.raven_context[:original_error]).to be_instance_of(JSON::ParserError)
+    end)
+  end
+
   it "generates server rendered HTML if server renderering enabled for shared redux" do
     get server_side_hello_world_shared_store_path
     html_nodes = Nokogiri::HTML(response.body)