WEB-3513: Parsing errors in chapter metadata are now labelled

app/lib/linting/linter.rb

@@ -20,7 +20,7 @@ def lint(options: {})
       output
     end
 
-    def lint_with_ui(options:, show_ui: true) # rubocop:disable Metrics/MethodLength
+    def lint_with_ui(options:, show_ui: true) # rubocop:disable Metrics/MethodLength, Metrics/AbcSize
       with_spinner(title: 'Checking {{bold:publish.yaml}} exists', show: show_ui) do
         check_publish_file_exists
       end
@@ -31,6 +31,11 @@ def lint_with_ui(options:, show_ui: true) # rubocop:disable Metrics/MethodLength
       end
       return unless annotations.blank?
 
+      with_spinner(title: 'Attempting to parse book', show: show_ui) do
+        book
+      end
+      return unless annotations.blank?
+
       with_spinner(title: 'Validating image references', show: show_ui) do
         annotations.concat(Linting::ImageLinter.new(book: book).lint)
       end
@@ -78,11 +83,23 @@ def check_publish_file_exists
       false
     end
 
-    def book
+    def book # rubocop:disable Metrics/MethodLength
       @book ||= begin
         parser = Parser::Publish.new(file: file)
         parser.parse
       end
+    rescue Parser::Error => e
+      line_number = (e.message.match(/at line (\d+)/)&.captures&.first&.to_i || 0) + 1
+      annotations.push(
+        Annotation.new(
+          absolute_path: e.file,
+          annotation_level: 'failure',
+          start_line: line_number,
+          end_line: line_number,
+          message: e.message,
+          title: 'Unable to parse book.'
+        )
+      )
     end
   end
 end

app/lib/parser/error.rb

@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+module Parser
+  # An error for capturing parsing issues
+  class Error < StandardError
+    attr_reader :file
+
+    def initialize(file:, error: nil, msg: nil)
+      message = "There was a problem parsing #{file}"
+      message += "\n#{error.class.name}\n#{error.message}" if error.present?
+      message += "\n#{msg}" if msg.present?
+
+      super(message)
+      @file = file
+    end
+  end
+end

app/lib/parser/markdown_metadata.rb

@@ -12,7 +12,13 @@ def extract_metadata
     end
 
     def metadata
-      @metadata ||= Psych.load(extract_metadata).deep_symbolize_keys
+      @metadata ||= begin
+        Psych.load(extract_metadata, symbolize_names: true).tap do |metadata|
+          raise Parser::Error.new(file: path, msg: 'Unable to locate metadata at the top of the markdown') unless metadata.present?
+        end
+      end
+    rescue Psych::SyntaxError => e
+      raise Parser::Error.new(file: path, error: e)
     end
 
     def simple_attributes