__block variables have been capture by the block，but 'dispose_helper' error

[zjutwhw]

__block variables have been capture by the block，but 'dispose_helper' error , Demo：

__weak CDItem *item = [CDItem new];
__block NSInteger index = 10;
void (^callblock)(NSString *name) = ^(NSString *name){
item.name = name;
index = 20;
};
callblock(@"jack");
void *block = (__bridge void *)callblock;
NSIndexSet *set = GetBlockStrongLayout(block); // FBBlockStrongLayout中_GetBlockStrongLayout(...)实现

error：
dispose_helper -- Thread 1: EXC_BAD_ACCESS (code=1, address=0x10)

[zjutwhw]