Fixes parsing certificate responses without machineName or machineId

Author: rileytestut

AltSign/Model/Apple API/ALTCertificate.m

@@ -47,7 +47,16 @@ - (instancetype)initWithResponseDictionary:(NSDictionary *)responseDictionary
     }
 
     NSString *machineName = attributesDictionary[@"machineName"];
+    if ([machineName isKindOfClass:[NSNull class]])
+    {
+        machineName = nil;
+    }
+    
     NSString *machineIdentifier = attributesDictionary[@"machineId"];
+    if ([machineIdentifier isKindOfClass:[NSNull class]])
+    {
+        machineIdentifier = nil;
+    }
 
     if (data != nil)
     {