"site can’t provide a secure connection" enabling https at the command line

[erictheise]

alive-server seems the most viable solution to our problem of developing map styles for the OpenHistoricalMap project. We have been firing up http-server using a script in our package.json but there's interest in having the browser refresh when map styles are edited.

I am having trouble with the --https=PATH option; I am using

import { readFileSync } from 'fs';

export default {
	cert: readFileSync("./ssl/cert.pem"),
	key: readFileSync("./ssl/key.pem")
};

to access the cert and key we use successfully with http-server but am getting this error:

This site can’t provide a secure connection
127.0.0.1 uses an unsupported protocol.
ERR_SSL_VERSION_OR_CIPHER_MISMATCH
Unsupported protocol
The client and server don't support a common SSL protocol version or cipher suite.

Our map style sheets need to call locally hosted instances of font glyphs and sprites.

I don't understand the unsupported protocol error, don't know how to proceed, and welcome your suggestions. Thanks.