unmarshalHex() panics if the public key submitted to UnmarshalText() has more than 64 hex digits

[mike76-dev]

The panic happens in hex.Decode if the submitted public key cannot fit in 32 bytes.
Should return an error instead.

func unmarshalHex(dst []byte, prefix string, data []byte) error {
	n, err := hex.Decode(dst, bytes.TrimPrefix(data, []byte(prefix+":")))
	if n < len(dst) {
		err = io.ErrUnexpectedEOF
	}
	if err != nil {
		return fmt.Errorf("decoding %v:<hex> failed: %w", prefix, err)
	}
	return nil
}

[lukechampine]

Good catch!