Don't use an uninitialized instance variables

lib/bugsnag.rb

@@ -43,6 +43,7 @@ def configure(config_hash=nil)
       require "bugsnag/delay/resque" if configuration.delay_with_resque && defined?(Resque)
 
       # Log that we are ready to rock
+      @logged_ready = nil unless defined?(@logged_ready)
       if configuration.api_key && !@logged_ready
         log "Bugsnag exception handler #{VERSION} ready, api_key=#{configuration.api_key}"
         @logged_ready = true
@@ -94,7 +95,8 @@ def debug(message)
 
     # Configuration getters
     def configuration
-      @configuration || LOCK.synchronize { @configuration ||= Bugsnag::Configuration.new }
+      return @configuration if defined?(@configuration)
+      LOCK.synchronize { @configuration = Bugsnag::Configuration.new }
     end
 
     # Set "per-request" data, temporal data for use in bugsnag middleware

lib/bugsnag/configuration.rb

@@ -102,6 +102,7 @@ def ignore_classes
     end
 
     def should_notify?
+      @notify_release_stages = nil unless defined?(@notify_release_stages)
       @release_stage.nil? || @notify_release_stages.nil? || @notify_release_stages.include?(@release_stage)
     end
 

lib/bugsnag/delivery/thread_queue.rb

@@ -26,6 +26,7 @@ def deliver(url, body, configuration)
 
         def start_once!
           MUTEX.synchronize do
+            @started = nil unless defined?(@started)
             return if @started
             @started = true
 

lib/bugsnag/notification.rb

@@ -153,6 +153,7 @@ def severity=(severity)
     end
 
     def severity
+      @severity = nil unless defined?(@severity)
       @severity || "warning"
     end
 
@@ -165,6 +166,7 @@ def grouping_hash=(grouping_hash)
     end
 
     def grouping_hash
+      @grouping_hash = nil unless defined?(@grouping_hash)
       @grouping_hash || nil
     end
 
@@ -226,6 +228,7 @@ def deliver
         Bugsnag.log("Notifying #{endpoint} of #{@exceptions.last.class} from api_key #{api_key}")
 
         # Deliver the payload
+        @delivery_method = nil unless defined?(@delivery_method)
         self.class.deliver_exception_payload(endpoint, build_exception_payload, @configuration, @delivery_method)
       end
     end