Add error handling on `read_page` (fixes #281)

src/library/entry.cr

@@ -144,14 +144,18 @@ class Entry
   def read_page(page_num)
     raise "Unreadble archive. #{@err_msg}" if @err_msg
     img = nil
+    begin
       sorted_archive_entries do |file, entries|
         page = entries[page_num - 1]
         data = file.read_entry page
         if data
-        img = Image.new data, MIME.from_filename(page.filename), page.filename,
-          data.size
+          img = Image.new data, MIME.from_filename(page.filename),
+            page.filename, data.size
         end
       end
+    rescue e
+      Logger.warn "Unable to read page #{page_num} of #{@zip_path}. Error: #{e}"
+    end
     img
   end