fix IsZero bug in std/math/emulated/field_assert.go

[readygo67]

Description

Fix the IsZero() bug in std/math/emulated/field_assert.go

Fixes # (issue)
#980

Type of change

• Bug fix (non-breaking change which fixes an issue)

How has this been tested?

zero and Non-zero tests have been implemented in field_assert_test.go

How has this been benchmarked?

No benchmark has been done

Checklist:

• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• I did not modify files generated from templates
• golangci-lint does not output errors locally
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

[CLAassistant]

All committers have signed the CLA.

[ivokub]

It is a perfect contribution. Thank you for reporting the issue and contributing a patch!