Failed to find any PEM data in key - go

Question

I am trying to run an HTTPS rest server locally.
I followed this help: Golang TLS
It works fine when using self-signed certificates as in the above tutorial.
But when I replace these certificates with one I generated from GoDaddy for one of my websites, I get ListenAndServe: tls: failed to find any PEM data in key input
These certificates work properly on the apache server but not on my local Go server.
package main
import (
"log"
"net/http"
)
func HelloServer(w http.ResponseWriter, req *http.Request) {
w.Header().Set("Content-Type", "text/plain")
_, _ = w.Write([]byte("This is an example server.\n"))
}
func main() {
//https://localhost:443/hello
http.HandleFunc("/hello", HelloServer)
err := http.ListenAndServeTLS(":443",
"../../../../../sslcert/server.crt",
"../../../../../sslcert/server.key",
nil)
if err != nil {
log.Fatal("ListenAndServe: ", err)
}
}

Answer 1

The issue was with the key file. The beginning of the file had some issue (like UTF-8 BOM at the start of the file or similar) as #SteffenUllrich mentioned. To fix this, I added an empty line just above the key file and it worked.
Finally, the key looks like:
<Empty line>
-----BEGIN RSA PRIVATE KEY-----
wlWPpSnGEdNjRapfW/6+xzjDVAaKC41c5b07OAviFchwqGI+88
aZGwBJnTgkbsLddddddd=
-----END RSA PRIVATE KEY-----

Answer 2

For me additional byte was added at the end, while serializing the data from the terminal, used below snippet to correct it.
func convert(input []byte) (output []byte) {
if input[len(input)-1] == 0 {
input = input[:len(input)-1]
}
return input
}