add nil handle

ZMediumToMarkdown.gemspec

@@ -6,7 +6,7 @@ Gem::Specification.new do |gem|
     gem.files         = Dir['lib/**/*.*']
     gem.executables   = ['ZMediumToMarkdown']
     gem.name          = 'ZMediumToMarkdown'
-    gem.version       = '2.1.2'
+    gem.version       = '2.1.3'
 
     gem.license       = "MIT"
 

lib/Helper.rb

@@ -99,22 +99,22 @@ def self.downloadLatestVersion()
     end
 
     def self.createPostInfo(postInfo, isForJekyll)
-        title = postInfo.title.gsub("[","")
-        title = title.gsub("]","")
+        title = postInfo.title&.gsub("[","")
+        title = title&.gsub("]","")
 
         tags = ""
         if !postInfo.tags.nil? && postInfo.tags.length > 0
-            tags = "\"#{postInfo.tags.map { |tag| tag.gsub("\"", "\\\"") }.join("\",\"")}\""
+            tags = "\"#{postInfo.tags.map { |tag| tag&.gsub("\"", "\\\"") }.join("\",\"")}\""
         end
 
         result = "---\n"
-        result += "title: \"#{title.gsub("\"", "\\\"")}\"\n"
-        result += "author: \"#{postInfo.creator.gsub("\"", "\\\"")}\"\n"
+        result += "title: \"#{title&.gsub("\"", "\\\"")}\"\n"
+        result += "author: \"#{postInfo.creator&.gsub("\"", "\\\"")}\"\n"
         result += "date: #{postInfo.firstPublishedAt.strftime('%Y-%m-%dT%H:%M:%S.%L%z')}\n"
         result += "last_modified_at: #{postInfo.latestPublishedAt.strftime('%Y-%m-%dT%H:%M:%S.%L%z')}\n"
-        result += "categories: \"#{postInfo.collectionName.gsub("\"", "\\\"")}\"\n"
+        result += "categories: \"#{postInfo.collectionName&.gsub("\"", "\\\"")}\"\n"
         result += "tags: [#{tags}]\n"
-        result += "description: \"#{postInfo.description.gsub("\"", "\\\"")}\"\n"
+        result += "description: \"#{postInfo.description&.gsub("\"", "\\\"")}\"\n"
         if !postInfo.previewImage.nil?
             result += "image:\r\n"
             result += "  path: #{postInfo.previewImage}\r\n"

lib/ZMediumFetcher.rb

@@ -238,7 +238,7 @@ def downloadPost(postURL, pathPolicy)
 
         if File.file?(absolutePath)
             lines = File.foreach(absolutePath).first(15)
-            if lines.first.start_with?("---")
+            if lines.first&.start_with?("---")
                 dateLine = lines.select { |line| line.start_with?("last_modified_at:") }.first
                 if !dateLine.nil?
                     fileLatestPublishedAt = Time.parse(dateLine[/^(last_modified_at:)\s+(\S*)/, 2]).to_i