Hmm. That’s interesting.
The problem is that these errors are somewhat hard to reproduce. All this time I’ve been developing the plugin, I’ve never come across this error, and I’ve been testing withdrawals in almost every release. It’s possible that only certain numbers cause this error. Also, I don’t know about OASIS.
In any case, it seems we have the following requirements:
1. Not too many digits
2. Must be a float, not string
Therefore the solution is the PHP round function. Is it possible for you to test OASIS again with this? My tests indicate that Bitcoin core accepts it.
$amount = round( $amount, 8 );
$result = $this->rpc->sendtoaddress(
"$address",
$amount,
"$comment",
"$comment_to"
);
It should work with both wallets.