v3.0.2
This should obviously print "true":
blob = new Blob(["self.onmessage = function() {};"], { type: "text/javascript" });
worker = new Worker(window.URL.createObjectURL(blob));
console.log(worker instanceof Worker);
However in some rare cases, it will print "false" in Safari. This caused bugs in prior versions of promise-worker-bi, but this release includes a workaround.