Ensure get_current_screen() returns WP_Screen|null

[marian1]

Currently, get_current_screen() simply checks whether the global variable $current_screen is set before returning it. Since global variables may be overridden, it should confirm that $current_screen is actually a WP_Screen object to ensure that get_current_screen() reliably returns a valid WP_Screen object.

Trac ticket: https://core.trac.wordpress.org/ticket/62562

[abcd95]

Test Report

Description

This report validates that the indicated patch works as expected.

Environment

• WordPress: 6.8-alpha-59274-src
• PHP: 8.2.25
• Server: nginx/1.27.2
• Database: mysqli (Server: 8.0.40 / Client: mysqlnd 8.2.25)
• Browser: Chrome 131.0.0.0
• OS: macOS

Actual Results

✅ Issue addressed by the patch.

[im3dabasia1]

Test Report

Description

This report validates whether the indicated patch works as expected.

Patch tested: ​https://github.com/WordPress/wordpress-develop/pull/7885.diff

Environment

• WordPress: 6.8-alpha-59274-src
• PHP: 8.2.25
• Server: nginx/1.27.2
• Database: mysqli (Server: 8.0.40 / Client: mysqlnd 8.2.25)
• Browser: Chrome 129.0.0.0
• OS: macOS
• Theme: Twenty Twenty-Five 1.0
• MU Plugins: None activated
• Plugins:
  • Test Reports 1.2.0

Actual Results

1. ✅ Issue resolved with patch.

[SergeyBiryukov]

In 61484:

Administration: Ensure get_current_screen() returns WP_Screen or null.

This adds a check that the $current_screen global is not only defined, but also has the correct type.

Follow-up to [15746].

Props marian1, mayanktripathi32, abcd95, im3dabasia1, SergeyBiryukov.
Fixes #62562.