Fixing mega menu when pathname is undefined

[LucasCalazans]

Description

Fixing an error when the user goes to /undefined route.

The useMegaMenu talon was understanding that is the default category, causing the error

Related Issue

Closes #3192.

Acceptance

Verification Steps

• Access this route /undefined
• The store should show a not found page with no error

Verification Stakeholders

Specification

Test Plan

• Access this route /undefined
• The store should show a not found page

Test scenario(s) for direct fix/feature

• Access this route /undefined
• The store should show a not found page

Test scenario(s) for any existing impacted features/areas

Test scenario(s) for any Magento Backend Supported Configurations

Is Browser/Device testing needed?

No

Any ad-hoc/edge case scenarios that need to be considered?

No

Screenshots / Screen Captures

Breaking Changes (if any)

Checklist

• I have added tests to cover my changes, if necessary.
• I have added translations for new strings, if necessary.
• I have updated the documentation accordingly, if necessary.

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QA

📝 In progress

• MFTF
• Cypress
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