Lightwalletd does not recover from failed launch

[pacu]

I'm running cashed and this version of lwd locally. I usually launch Zcashd and then lwd without paying too much attention to it.
I noticed that some of my tests that fetch old block ranges were failing.

Steps:

1. launch zcashd locally
2. launch lwd right after without letting Zcashd finish initializing.
3. let lwd launch
4. call a service to get an old block range (e.g. 280000 to 280100)

expected: request succeeds
result: request fails with unknown status code

console is stuck on

WARNING[2019-12-05T12:35:07-03:00] Unable to get sapling activation height       app=frontend-grpc error="error requesting block: -28: Loading block index..."
INFO[2019-12-05T12:35:07-03:00] Got sapling height -1 chain  branchID         app=frontend-grpc
INFO[2019-12-05T12:35:07-03:00] Starting gRPC server on 127.0.0.1:9067        app=frontend-grpc
WARNING[2019-12-05T12:35:22-03:00] error with getblock                           app=frontend-grpc error="error requesting block: -28: Loading block index..." height=-1
WARNING[2019-12-05T12:35:37-03:00] error with getblock                           app=frontend-grpc error="error requesting block: -28: Loading block index..." height=-1

[LarryRuane]

This will be fixed by zcash#149 (sorry it did not get its own PR over in that repo). @pacu, if it is possible and convenient for you to test that branch, please do so and confirm that the problem is fixed there. If so, it probably doesn't need to be fixed here (but of course that's up to Aditya).

[pacu]

Sure, let me check it out.