fix: clamp negative job delay values to 0 to prevent thrashing

lib/job.js

@@ -34,7 +34,7 @@ const Job = function(queue, name, data, opts) {
   this.queue = queue;
   this.data = data;
   this._progress = 0;
-  this.delay = this.opts.delay;
+  this.delay = this.opts.delay < 0 ? 0 : this.opts.delay;
   this.timestamp = this.opts.timestamp;
   this.stacktrace = [];
   this.returnvalue = null;