Only replace default Sidekiq error handler when present

for Sidekiq >= v6.5, < V7

Author: reidmorrison

README.md

@@ -87,7 +87,7 @@ The queue latency is the time between when the job was enqueued and when it was
 filter environment = "production"
 filter level = "info"
 filter metric = "sidekiq.queue.latency"
-timechart latency:avg(metric_amount), group_by(name)
+timechart latency:avg(metric_amount/1000), group_by(string(named_tags.queue))
 ~~~
 
 * http://github.com/reidmorrison/rails_semantic_logger

lib/rails_semantic_logger/extensions/sidekiq/sidekiq.rb

@@ -129,9 +129,9 @@ class Config
         end
       end
     end
-  else
+  elsif Sidekiq.error_handlers.delete(Sidekiq::DEFAULT_ERROR_HANDLER)
     # Sidekiq >= 6.5
-    Sidekiq.error_handlers.delete(Sidekiq::DEFAULT_ERROR_HANDLER)
+    # Replace default error handler if present
     Sidekiq.error_handlers << ->(ex, ctx) do
       unless ctx.empty?
         job_hash = ctx[:job] || {}