System information

Geth version: v1.5.7
OS & Version: Windows/Linux/OSX
Commit hash : (if develop)

take DelayLeftOver for example:
it has default value: 50ms
https://github.com/bnb-chain/bsc/blob/v1.5.7/miner/minerconfig/config.go#L56

if a validator have the following setup in its config.toml

[Eth.Miner]
GasCeil = 140000000
GasFloor = 140000000
GasPrice = 1000000000
Recommit = 10000000000
VoteEnable = true

obviously, DelayLeftOver is not set.

Expected behaviour

• we expect it use the default 50ms

Actual behaviour

• but it is 0 actually

Steps to reproduce the behaviour

NA, mark: there are lots of such kind of cases, need to be improved.

Backtrace

NA