[Issue] Fix: Allow to fetch tax class ID for NOT LOGGED IN customer group

[m2-assistant]

This issue is automatically created based on existing pull request: #39822: Fix: Allow to fetch tax class ID for NOT LOGGED IN customer group

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Description (*)

When using \Magento\Catalog\Helper\Data::getTaxPrice to fetch price, tax details are miscalculated for context with guest users.

Here the group id 0 was interpreted as NULL while it shouldn't.

Contribution checklist (*)

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• README.md files for modified modules are updated and included in the pull request if any README.md predefined sections require an update
• All automated tests passed successfully (all builds are green)

[engcom-November]

Hello @thomas-kl1 ,

Thank for your report and collaboration.

However, we’re currently unable to identify the exact issue. Could you please provide the following details to help us review it more effectively:

• A clear description of the issue
• Steps to reproduce it
• Expected vs. actual results
• A screencast or screenshots, if possible

This information will greatly assist us in understanding and addressing the issue.

Hence marking this issue as "Needs Update"

Thank you!

[thomas-kl1]

When Magento render the product price on the frontend, it completely ignore the tax class ID for the customer group "Not Logged In", if the visitor is a guest. The tax class is then resolved from the product as default.
The fix is really easy as seen in the suggested change, it's because the comparison implicitly cast the customer group ID "0" as null. That's why the strict comparison is necessary.