Copying a BASIC program alerts constantly with "problematic byte 13"

[mattgodbolt]

I fixed an error where this.emulator.readmem wasn't defined. But...looks like there's code that alerts all the time:

                while (len--) {
                    let b = this.emulator.readmem(addr++);
                    if (b < 32 || (b >= 127 && b < 161)) {
                        if (b == 10 || b == 13) alert("problematic byte value " + b);
                        b += 0x100;
                    }
                    data += String.fromCodePoint(b);
                }

@8bitkick I'm not sure what this is supposed to do but copying any memory pretty much kills the browser with this (as it has a modal alert up)

[ojwb]

Sadly @8bitkick broke my saving memory feature - I pointed this out in #96 nearly 2 years ago but I never got a response...