[Bug]: GetParams errors when introducing new param

[czarcas7ic]

Is there an existing issue for this?

• I have searched the existing issues

What happened?

What happened:

When introducing a new parameter, the new parameter must be manually set, even if the desired value of that parameter is nil. See the following upgrade handler: https://github.com/osmosis-labs/osmosis/blob/54261649fd3d1e372749261430de642cebd9e95a/app/upgrades/v20/upgrades.go#L13-L32

RunMigrations is run which calls initGenesis. If I were to cal GetParams in the upgrade handler, we would get the following error (truncated for brevity):

"recovered: UnmarshalJSON cannot decode empty bytes\nstack:\ngoroutine 178
          [running]:\nruntime/debug.Stack()\n\truntime/debug/stack.go:24 +0x64\ngithub.com/cosmos/cosmos-sdk/baseapp.newDefaultRecoveryMiddleware.func1({0x231a320,
          0x400649f960})\n\tgithub.com/cosmos/[email protected]/baseapp/recovery.go:71 +0x24\ngithub.com/cosmos/cosmos-sdk/baseapp.newRecoveryMiddleware.func1({0x231a320?,
          0x400649f960?})\n\tgithub.com/cosmos/[email protected]/baseapp/recovery.go:39 +0x34\ngithub.com/cosmos/cosmos-sdk/baseapp.processRecovery({0x231a320,
          0x400649f960}, 0x400000e270?)\n\tgithub.com/cosmos/[email protected]/baseapp/recovery.go:28
          +0x38\ngithub.com/cosmos/cosmos-sdk/baseapp.processRecovery({0x231a320, 0x400649f960},
          0x2df5560?)\n\tgithub.com/cosmos/[email protected]/baseapp/recovery.go:33 +0x60\ngithub.com/cosmos/cosmos-sdk/baseapp.(*BaseApp).runTx.func1()\n\tgithub.com/cosmos/[email protected]/baseapp/baseapp.go:620
          +0xa8\npanic({0x231a320, 0x400649f960})\n\truntime/panic.go:884 +0x1f4\ngithub.com/cosmos/cosmos-sdk/x/params/types.Subspace.Get({{_,
          _}, _, {_, _}, {_, _}, {_, _, _}, ...}, ...)\n\tgithub.com/cosmos/[email protected]/x/params/types/subspace.go:109
          +0x20c\ngithub.com/cosmos/cosmos-sdk/x/params/types.Subspace.GetParamSet({{_, _},

You also can't use SetParams, since that would require you to call GetParams to get the current state which would have the same error above. To get around this, I exposed the Set command at each module so we can manually set the new value in the upgrade handler.

My recommendation would be that, when a new value gets added to the ParamKeyTable, the DefaultValue of that type is automatically assigned. This would allow for simpler manipulation at the upgrade handler level rather than hacking around it as I did.

Not really a massive issue, just a QoL that will likely save other chains time in the future.

Cosmos SDK Version

0.45 (osmosis fork)

How to reproduce?

No response

[tac0turtle]

Hey the params modules has been marked as maintenance mode only. We have migrated away from it for many reasons. Unfortunately we will not be able to fix this issue. I know osmosis is migrating to 0.50, this will fix your issue