only assert opened state for in-house db connections

Author: timgit

src/manager.js

@@ -680,9 +680,9 @@ class Manager extends EventEmitter {
       return options.db
     }
 
-    // Custom db objects (without _pgbdb flag) are assumed to be ready
-    // Only check opened flag for pg-boss managed db instances
-    assert(!this.db._pgbdb || (this.db._pgbdb && this.db.opened), 'Database connection is not opened')
+    if (this.db._pgbdb) {
+      assert(this.db.opened, 'Database connection is not opened')
+    }
 
     return this.db
   }