fix: update param validation to fail on nil dec (backport #1323)

[mergify[bot]]

Description

• fix: update param validation to fail on nil dec
  • refer: https://github.com/cosmos/cosmos-sdk/pull/13553

Motivation and context

How has this been tested?

Screenshots (if appropriate):

Checklist:

• [x] I followed the contributing guidelines and code of conduct.
• [x] I have added a relevant changelog to CHANGELOG.md
• [ ] I have added tests to cover my changes.
• [ ] I have updated the documentation accordingly.
• [ ] I have updated API documentation client/docs/swagger-ui/swagger.yaml

  ---

  This is an automatic backport of pull request #1323 done by Mergify.

[mergify[bot]]

Cherry-pick of 55b6566bf3c0811a7e758dd166c980de343ad1f3 has failed:

On branch mergify/bp/release/v0.48.x/pr-1323
Your branch is up to date with 'origin/release/v0.48.x'.

You are currently cherry-picking commit 55b6566bf.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
    modified:   x/mint/types/params.go
    modified:   x/slashing/types/params.go

Unmerged paths:
  (use "git add <file>..." to mark resolution)
    both modified:   CHANGELOG.md

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 0% with 21 lines in your changes are missing coverage. Please review.

Project coverage is 69.74%. Comparing base (69a3ec7) to head (696d83e).

Additional details and impacted files

[](https://app.codecov.io/gh/Finschia/finschia-sdk/pull/1325?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Finschia) ```diff @@ Coverage Diff @@ ## release/v0.48.x #1325 +/- ## =================================================== - Coverage 69.76% 69.74% -0.03% =================================================== Files 646 646 Lines 67573 67594 +21 =================================================== Hits 47142 47142 - Misses 18242 18263 +21 Partials 2189 2189 ``` | [Files](https://app.codecov.io/gh/Finschia/finschia-sdk/pull/1325?dropdown=coverage&src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Finschia) | Coverage Δ | | |---|---|---| | [x/slashing/types/params.go](https://app.codecov.io/gh/Finschia/finschia-sdk/pull/1325?src=pr&el=tree&filepath=x%2Fslashing%2Ftypes%2Fparams.go&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Finschia#diff-eC9zbGFzaGluZy90eXBlcy9wYXJhbXMuZ28=) | `0.00% <0.00%> (ø)` | | | [x/mint/types/params.go](https://app.codecov.io/gh/Finschia/finschia-sdk/pull/1325?src=pr&el=tree&filepath=x%2Fmint%2Ftypes%2Fparams.go&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Finschia#diff-eC9taW50L3R5cGVzL3BhcmFtcy5nbw==) | `6.47% <0.00%> (-0.62%)` | :arrow_down: |