Crash on mono_class_is_blittable when calling UnsafeUtility.IsBlittable() and three sibling Type overloads with a null Type argument

How to reproduce:

1. Open the attached “repro-crash” project
2. In the menu bar, select “Bug Repro” > “UnsafeUtility null Type” > “1. CrashIsBlittable”
3. Observe the crash

Reproducible with: 6000.0.0f1, 6000.0.81f1, 6000.3.22f1, 6000.5.8f1, 6000.6.0b9, 6000.7.0a5

Reproducible on: Ubuntu 24.04 LTS, Ubuntu 26.04 LTS (by user), Windows 10 Pro
Not reproducible on: No other environments tested

Notes:

• Reproducible with -batchmode -nographics
• Also reproducible when in step 2, “1. CrashIsBlittable” is replaced with one of these - “2. CrashIsUnmanaged”, “3. CrashSizeOf”, and “4. CrashIsValidNativeContainerElementType”
• The UnsafeUtility methods and the crashes with them:
  UnsafeUtility.IsBlittable(Type) exit -6 SIGABRT
  UnsafeUtility.IsUnmanaged(Type) exit -11 SIGSEGV
  UnsafeUtility.SizeOf(Type) exit -11 SIGSEGV
  UnsafeUtility.IsValidNativeContainerElementType(Type) exit -11 SIGSEGV

First few lines of the stack trace:

* Assertion at unity-utils.c:377, condition `klass' not met
Caught fatal signal - signo:6 code:-6 errno:0 addr:0x3e8000373db
#9  mono_class_is_blittable
#10 scripting_class_is_blittable(ScriptingClassPtr)
#11 UnsafeUtility_CUSTOM_IsBlittable(ScriptingBackendNativeObjectPtrOpaque*)
#12 (wrapper managed-to-native) Unity.Collections.LowLevel.Unsafe.UnsafeUtility:IsBlittable (System.Type)