Cannot convert 'StringSumHelper' to 'double'

I have a method that accepts a string:

void log(String message) {
  Serial.println(message);
}

I'm calling it like this:

log("write(" + String(angle + '0') + ");");

But I get this compilation error:

error: cannot convert 'StringSumHelper' to 'double' for argument '1' to 'double log(double)'
       log("write(" + String(angle + '0') + ");");
                                                ^
Compilation error: Error: 13 INTERNAL: exit status 1

What gives? Where's this double it's expecting/receiving coming from?

https://en.cppreference.com/w/cpp/numeric/math/log

You can't add angle (which I presume is a double) to a string because they are different types. I'm guessing that you want this:

log("write(" + String(angle) + "0);");

Angle is a byte, doesn't String() convert it to a String though?

Yes, you're right. I stuck the '0' inside the brackets. Dog! Thanks. I should have noticed that.