Review note: The changes are complete, because self.options.descriptors
is set to None in parse_args (test_framework.py).
A value of None implies -disablewallet, see the previous commit.
So if a call to add_wallet_options is missing, it will lead to a test
failure when the wallet is compiled in.
By throwing a custom exception from `Univalue::checkType` (instead of a plain
std::runtime_error) and catching it on the RPC server request handler.
So we properly return RPC_TYPE_ERROR (-3) on arg type errors and
not the general RPC_MISC_ERROR (-1).
The previous diff touched most files in ./test/, so bump the headers to
avoid having to touch them again for a bump later.
-BEGIN VERIFY SCRIPT-
./contrib/devtools/copyright_header.py update ./test/
-END VERIFY SCRIPT-