Avoid a boot-time dependency on the database

Some environments (e.g., test) may not create the database, and so we
should check that the table exists (which uses the schema cache) to
skip the column lookup and the pending-migration warning.

Author: flavorjones

app/models/solid_queue/claimed_execution.rb

@@ -2,13 +2,13 @@
 
 class SolidQueue::ClaimedExecution < SolidQueue::Execution
   def self.process_name_column_exists?
-    column_names.include?("process_name")
+    table_exists? && column_names.include?("process_name")
   end
 
   if process_name_column_exists?
     belongs_to :process, primary_key: :name, foreign_key: :process_name
   else
-    warn_about_pending_migrations
+    warn_about_pending_migrations if table_exists?
 
     belongs_to :process
     attr_accessor :process_name

app/models/solid_queue/process/executor.rb

@@ -9,7 +9,7 @@ module Executor
         if ClaimedExecution.process_name_column_exists?
           has_many :claimed_executions, primary_key: :name, foreign_key: :process_name
         else
-          warn_about_pending_migrations
+          warn_about_pending_migrations if ClaimedExecution.table_exists?
 
           has_many :claimed_executions
         end