Test errors don't throw in correct conditions

test/errors.js

@@ -27,10 +27,16 @@ test('Vain throws when `options.prefix` is `undefined`', t => {
 	const options = {};
 	const error = t.throws(() => new Vain(options));
 	t.is(error.message, 'Prefix must be set');
+
+	options.prefix = 'BTC';
+	t.notThrows(() => new Vain(options));
 });
 
 test('Vain throws when `options.xpub` is `undefined` when `options.keyFormat` is `xpub`', t => {
 	const options = {keyFormat: 'xpub', prefix: 'BTC'};
 	const error = t.throws(() => new Vain(options));
 	t.is(error.message, 'An xpub string must be passed in');
+
+	options.xpub = 'xpub6EDZZg3os4RaLxfPpnGBb7ajm6ccyjRs3PGZ5jNK31rPnbpyKb7dc87cEPaLEjFYDBGCQT8VMm8q8MVj2tj7HPBu8syxu82cdHLCNaQmT42';
+	t.notThrows(() => new Vain(options));
 });