Tested versions

I tracked it down to being introduced in commit 72a1b5a
which merges PR #108607 from @beicause

System information

Godot v4.6.dev (72a1b5a) - Windows 11 (build 22631) - Single-window, 4 monitors - OpenGL 3 (Compatibility) - NVIDIA GeForce RTX 2080 SUPER (NVIDIA; 32.0.15.8157) - 12th Gen Intel(R) Core(TM) i9-12900K (24 threads) - 63.78 GiB memory

Issue description

The editor crashes when opening certain pages that don't have icons in the integrated documentation/help viewer.

Steps to reproduce

Help -> Search Help -> double click @GDScript or @GlobalScope -> crash

Minimal reproduction project (MRP)

This is not needed. see steps above.