message: change error message to ensureActualIsNumber
diff: @@ -153,7 +153,7 @@ const ensureActualIsNumber = (actual: any, matcherName: string) => {
  if (typeof actual !== 'number') {
  throw new Error(
  matcherHint('[.not]' + matcherName) + '\n\n' +
  - `Actual value must be a number.\n` +
  + `Received value must be a number.\n` +
  printWithType('Received', actual, printReceived),
  );
  }
  