Adds fix for corrupt PDF error from MUSE

spec/fetch_spec.cr

@@ -0,0 +1,12 @@
+require "./spec_helper"
+# require "errors/muse_corrupt_pdf.cr"
+
+describe Muse::Dl::Book do
+  it "should notice the unable to construct chapter PDF error" do
+    f = "/tmp/chapter-2379787.pdf"
+    File.delete(f) if File.exists? f
+    expect_raises Muse::Dl::Errors::MuseCorruptPDF do
+      Muse::Dl::Fetch.save_chapter("/tmp", "2379787", "NA")
+    end
+  end
+end

src/errors/muse_corrupt_pdf.cr

@@ -0,0 +1,4 @@
+module Muse::Dl::Errors
+  class MuseCorruptPDF < Exception
+  end
+end

src/fetch.cr

@@ -1,5 +1,6 @@
 require "crest"
 require "./errors/*"
+require "myhtml"
 
 module Muse::Dl
   class Fetch
@@ -42,6 +43,18 @@ module Muse::Dl
 
       # TODO: Add validation for the downloaded file (should be PDF)
       Crest.get(url, max_redirects: 0, handle_errors: false, headers: headers) do |response|
+        # puts response.headers["Content-Type"]
+        content_type = response.headers["Content-Type"]
+        if content_type.is_a? String
+          if /html/.match content_type
+            puts response
+            response.body_io.each_line do |line|
+              if /Unable to construct chapter PDF/.match line
+                raise Muse::Dl::Errors::MuseCorruptPDF.new
+              end
+            end
+          end
+        end
         File.open(tmp_pdf_file, "w") do |file|
           IO.copy(response.body_io, file)
         end

src/muse-dl.cr

@@ -33,7 +33,12 @@ module Muse::Dl
         unless parser.input_pdf
           # Save each chapter
           thing.chapters.each do |chapter|
-            Fetch.save_chapter(parser.tmp, chapter[0], chapter[1], parser.cookie, parser.bookmarks)
+            begin
+              Fetch.save_chapter(parser.tmp, chapter[0], chapter[1], parser.cookie, parser.bookmarks)
+            rescue e : Muse::Dl::Errors::MuseCorruptPDF
+              STDERR.puts "Got a 'Unable to construct chapter PDF' error from MUSE, skipping: #{url}"
+              return
+            end
           end
           chapter_ids = thing.chapters.map { |c| c[0] }