Block threads (esp the main thread) from entering the runtime from the JS event loop when a GC Stop-The-World is active.
The thread should safepoint in native, or (better) somehow defer its work and return to the JS event loop

Current offenders are

• reflection in init_managed_exports
• mono_wasm_gc_lock, mono_wasm_gc_unlock used by Blazor
• mono_wasm_read_as_bool_or_null_unsafe used by Blazor
• GC roots in hybrid globalization