html - Handle error message when displaying PDF in an IFrame -

i'm trying display pdf in browser when clicked on it. i'm creating iframe , setting pdf url src. works fine when url returns 200 , can display pdf in iframe.

problem is, when request pdf url fails(returns other 200), iframe displays response.

so iframe show text, response of http on pdf url.

{"message":"pdf unavailable"} 

how handle error case , display custom message on iframe?

one alternative method load pdf in iframe use new pdfobject.
may setup pdfloader within , , use javascript snippet embed pdf. var mypdf = new pdfobject({
url: "http://example.com/def.pdf",
id: "pdfrendered",
pdfopenparams: {
view: "fith"
}
}).embed("pdfloader");