style(rubocop): Lint/UselessAssignment

app/controllers/ip_pools_controller.rb

@@ -33,7 +33,7 @@ class IPPoolsController < ApplicationController
   def destroy
     @ip_pool.destroy
     redirect_to_with_json :ip_pools, notice: "IP pool has been removed successfully."
-  rescue ActiveRecord::DeleteRestrictionError => e
+  rescue ActiveRecord::DeleteRestrictionError
     redirect_to_with_json [:edit, @ip_pool], alert: "IP pool cannot be removed because it still has associated addresses or servers."
   end
 

app/controllers/messages_controller.rb

@@ -188,7 +188,7 @@ class MessagesController < ApplicationController
             if qs[:before]
               begin
                 options[:where][:timestamp][:less_than] = get_time_from_string(qs[:before]).to_f
-              rescue TimeUndetermined => e
+              rescue TimeUndetermined
                 flash.now[:alert] = "Couldn't determine time for before from '#{qs[:before]}'"
               end
             end
@@ -196,7 +196,7 @@ class MessagesController < ApplicationController
             if qs[:after]
               begin
                 options[:where][:timestamp][:greater_than] = get_time_from_string(qs[:after]).to_f
-              rescue TimeUndetermined => e
+              rescue TimeUndetermined
                 flash.now[:alert] = "Couldn't determine time for after from '#{qs[:after]}'"
               end
             end

app/controllers/sessions_controller.rb

@@ -10,7 +10,7 @@ class SessionsController < ApplicationController
     login(User.authenticate(params[:email_address], params[:password]))
     flash[:remember_login] = true
     redirect_to_with_return_to root_path
-  rescue Postal::Errors::AuthenticationError => e
+  rescue Postal::Errors::AuthenticationError
     flash.now[:alert] = "The credentials you've provided are incorrect. Please check and try again."
     render "new"
   end