specialops crash when the bitcore-node startup

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Call stack

[2018-04-02T12:21:06.225Z] warn: Reorg detected! Current tip: 0000000000000000000000000000000000000000000000000000000000000000
[2018-04-02T12:21:06.225Z] info: disconnecting block undefined undefined
[2018-04-02T12:21:06.227Z] warn: Disconnected current tip. New tip is 0000000000000000000000000000000000000000000000000000000000000000
[2018-04-02T12:21:06.240Z] error: uncaught exception: TypeError: Cannot read property 'rhash' of undefined
at /home/node/fullnode/bitcore/node_modules/specialops/lib/index.js:197:21
at /home/node/fullnode/bitcore/node_modules/bitcore-node/lib/services/block/index.js:471:14
at /home/node/fullnode/bitcore/node_modules/bitcore-node/lib/services/db/index.js:107:16
at /home/node/fullnode/bitcore/node_modules/levelup/lib/levelup.js:168:14
[2018-04-02T12:21:06.241Z] error: TypeError: Cannot read property 'rhash' of undefined
at /home/node/fullnode/bitcore/node_modules/specialops/lib/index.js:197:21
at /home/node/fullnode/bitcore/node_modules/bitcore-node/lib/services/block/index.js:471:14
at /home/node/fullnode/bitcore/node_modules/bitcore-node/lib/services/db/index.js:107:16
at /home/node/fullnode/bitcore/node_modules/levelup/lib/levelup.js:168:14

[qinfengling]

Fixed in 8c4fe67

The crash caused by invalid hash, when the block height is 0, the block hash is not assigned any value. so the reorg will fail.