print error more descriptive

lib/github_changelog_generator/fetcher.rb

@@ -60,6 +60,21 @@ module GitHubChangelogGenerator
       tags = []
 
       begin
+        github_fetch_tags(tags)
+      rescue Github::Error::Unauthorized => e
+        @logger.error e.body.red
+        @logger.error "Error: wrong github token provided".red
+      rescue Github::Error::Forbidden => e
+        @logger.warn e.body.red
+        unless @options[:token].nil?
+          @logger.warn GH_RATE_LIMIT_EXCEEDED_MSG.yellow
+        end
+      end
+
+      tags
+    end
+
+    def github_fetch_tags(tags)
       response = @github.repos.tags @options[:user], @options[:project]
       page_i = 0
       count_pages = response.count_pages
@@ -76,12 +91,6 @@ Make sure, that you push tags to remote repo via 'git push --tags'".yellow
       elsif @options[:verbose]
         @logger.info "Found #{tags.count} tags"
       end
-
-      rescue
-        @logger.warn GH_RATE_LIMIT_EXCEEDED_MSG.yellow
-      end
-
-      tags
     end
 
     # This method fetch all closed issues and separate them to pull requests and pure issues
@@ -108,6 +117,8 @@ Make sure, that you push tags to remote repo via 'git push --tags'".yellow
           break if @options[:max_issues] && issues.length >= @options[:max_issues]
         end
       rescue
+        puts e.message
+        puts e.backtrace.inspect
         @logger.warn GH_RATE_LIMIT_EXCEEDED_MSG.yellow
       end