(dot/sync): Fix bugs related to tip sync

[jimjbrettj]

Issue summary

• [ ] Sometimes when in tip sync mode the node will crash with an index out of bounds error (see 1)
• [x] On startup, sometimes the node will not begin and then when it's stopped it panics (see 2)
• [ ] Related to the above issue, sometimes before the spam logs we get errors from peerset (see 3)
• [ ] Sometimes we get to tip sync and don't progress (see 4)
• [ ] We also get this error every so often (see 5)