Unable to make preauthorization

[josippetric]

When preauthorization attempt is made in the VoucherMill application, application crashes with attached stack. Application is tested with test public key on the iOS 8.3 simulator with Xcode 6.3.
Edit: Issue is present on iOS 8.1 too, but preauthorization works as intended on the iOS 7.1 simulator.

Recreate issue:

1. Press "Test Log In"
2. Select "Buy voucher"
3. Select "Reserve"
4. Select "submit"
5. Enter test data for a test credit card
6. Press "Submit"

2015-06-08 18:07:59.406 VoucherMill[1335:68242] *** Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[<PMPreauthorization 0x7fd6536dbcd0> setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key description.'
*** First throw call stack:
(
0 CoreFoundation 0x00000001121cbc65 exceptionPreprocess + 165
1 libobjc.A.dylib 0x0000000111e64bb7 objc_exception_throw + 45
2 CoreFoundation 0x00000001121cb8a9 -[NSException raise] + 9
3 Foundation 0x00000001117b8b53 -[NSObject(NSKeyValueCoding) setValue:forKey:] + 259
4 VoucherMill 0x000000010fee8e34 +[PMAttributeSetter assingValue:forAttributeName:andAttributeClass:onObject:] + 420
5 VoucherMill 0x000000010feee230 -[PMKeyValueObjectMapping parseValue:forObject:inAttribute:] + 352
6 VoucherMill 0x000000010feed731 -[PMKeyValueObjectMapping setValuesOnObject:withDictionary:] + 881
7 VoucherMill 0x000000010feed377 -[PMKeyValueObjectMapping parseDictionary:] + 247
8 VoucherMill 0x000000010feebb03 -[PMGenericConverter transformValue:forDynamicAttribute:] + 499
9 VoucherMill 0x000000010feee1a6 -[PMKeyValueObjectMapping parseValue:forObject:inAttribute:] + 214
10 VoucherMill 0x000000010feed731 -[PMKeyValueObjectMapping setValuesOnObject:withDictionary:] + 881
11 VoucherMill 0x000000010feed377 -[PMKeyValueObjectMapping parseDictionary:] + 247
12 VoucherMill 0x000000010feebb03 -[PMGenericConverter transformValue:forDynamicAttribute:] + 499
13 VoucherMill 0x000000010feee1a6 -[PMKeyValueObjectMapping parseValue:forObject:inAttribute:] + 214
14 VoucherMill 0x000000010feed731 -[PMKeyValueObjectMapping setValuesOnObject:withDictionary:] + 881
15 VoucherMill 0x000000010feed377 -[PMKeyValueObjectMapping parseDictionary:] + 247
16 VoucherMill 0x000000010fee7ac5 +[PMJSONParser parseJSONResponse:onClass:error:] + 2565
17 VoucherMill 0x000000010fee4ab0 -[PMGenericResponseDelegate parseResponse:forClass:error:] + 112
18 VoucherMill 0x000000010fee69e7 -[PMTransactionResponseDelegate parseResponse:forClass:error:] + 167
19 VoucherMill 0x000000010fee5232 -[PMGenericResponseDelegate connectionDidFinishLoading:] + 1154
20 CFNetwork 0x0000000112e380bc __65-[NSURLConnectionInternal _withConnectionAndDelegate:onlyActive:]_block_invoke + 69
21 CFNetwork 0x0000000112e38060 -[NSURLConnectionInternal _withConnectionAndDelegate:onlyActive:] + 199
22 CFNetwork 0x0000000112e381c7 -[NSURLConnectionInternal _withActiveConnectionAndDelegate:] + 48
23 CFNetwork 0x0000000112d07757 ___ZN27URLConnectionClient_Classic26_delegate_didFinishLoadingEU13block_pointerFvvE_block_invoke + 107
24 CFNetwork 0x0000000112dd4de1 ___ZN27URLConnectionClient_Classic18_withDelegateAsyncEPKcU13block_pointerFvP16_CFURLConnectionPK33CFURLConnectionClientCurrent_VMaxE_block_invoke_2 + 273
25 CFNetwork 0x0000000112cf2a26 _ZN19RunloopBlockContext13_invoke_blockEPKvPv + 72
26 CoreFoundation 0x00000001120d2354 CFArrayApplyFunction + 68
27 CFNetwork 0x0000000112cf28e7 _ZN19RunloopBlockContext7performEv + 133
28 CFNetwork 0x0000000112cf2726 _ZN17MultiplexerSource7performEv + 256
29 CFNetwork 0x0000000112cf253c _ZN17MultiplexerSource8_performEPv + 72
30 CoreFoundation 0x00000001120ff431 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION + 17
31 CoreFoundation 0x00000001120f52fd __CFRunLoopDoSources0 + 269
32 CoreFoundation 0x00000001120f4934 __CFRunLoopRun + 868
33 CoreFoundation 0x00000001120f4366 CFRunLoopRunSpecific + 470
34 GraphicsServices 0x0000000114376a3e GSEventRunModal + 161
35 UIKit 0x00000001104b0900 UIApplicationMain + 1282
36 VoucherMill 0x000000010fea0b7f main + 111
37 libdyld.dylib 0x0000000113506145 start + 1
38 ??? 0x0000000000000001 0x0 + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException