Feeding subnet-evm with faulty upgrade.json results in panic

[holisticode]

Describe the bug
Install faulty upgrade.json to node:

{
  "precompileUpgrades": {
      "feeManagerConfig": {
        "blockTimestamp": 1668950000,
        "adminAddresses": ["0x8db97C7cEcE249c2b98bDC0226Cc4C2A57BF52FC"]
      }
    }
}

(might not be the exact upgrade.json which failed as it got overwritten now)

To Reproduce
Install faulty upgrade.json to node and start

Expected behavior
Should gracefully handle

Screenshots

INFO [01-26|14:57:25.580] <kXG6HvtqcSoEHhkbVDdhQukZNgMPeKqzqiaJ1znXjkH1Tpitg Chain> github.com/ava-labs/subnet-evm/eth/backend.go:134: Allocated memory caches trie clean=512.00MiB trie dirty=256.00MiB snapshot clean=256.00MiB
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x561a62]

goroutine 12 [running]:
math/big.(*Int).Cmp(0xac660b?, 0x0?)
        /opt/hostedtoolcache/go/1.18.9/x64/src/math/big/int.go:328 +0x22
github.com/ava-labs/subnet-evm/commontype.(*FeeConfig).Verify(0xc000638840)
        /home/runner/work/subnet-evm/subnet-evm/subnet-evm/commontype/fee_config.go:65 +0x2f
github.com/ava-labs/subnet-evm/precompile.(*FeeConfigManagerConfig).Verify(0xc0005d6280)
        /home/runner/work/subnet-evm/subnet-evm/subnet-evm/precompile/fee_config_manager.go:141 +0x3d
github.com/ava-labs/subnet-evm/params.(*ChainConfig).verifyPrecompileUpgrades(0xc0005ff320)
        /home/runner/work/subnet-evm/subnet-evm/subnet-evm/params/precompile_config.go:156 +0x230
github.com/ava-labs/subnet-evm/params.(*ChainConfig).Verify(0xc0005ff320)

Operating System
linux

[aaronbuchwald]

Addressed by #461

[ceyonur]

Hm this might be different than #461 since this one occured on fee config Verify. It seems like the given initial fee config has an empty field of gasLimit. We should be checking that in verify, thanks!

Created #473