Also assert that nNodeType is non-negative

...given that nNodeType aka AnimationNode::mnNodeType is later used as an index
into the AnimationNode::mpTypes array

Change-Id: Ic208fbdfaa8dcca44ff2a99cf3b169904b14a4bf
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/135203
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

animations/source/animcore/animcore.cxx

@@ -55,6 +55,7 @@
 
 #include <cppuhelper/implbase.hxx>
 
+#include <o3tl/safeint.hxx>
 #include <osl/mutex.hxx>
 #include <sal/log.hxx>
 #include <array>
@@ -446,7 +447,7 @@ AnimationNode::AnimationNode( sal_Int16 nNodeType )
     mnIterateType( css::presentation::ShapeAnimationSubType::AS_WHOLE ),
     mfIterateInterval(0.0)
 {
-    assert(nNodeType < int(mpTypes.size()));
+    assert(nNodeType >= 0 && o3tl::make_unsigned(nNodeType) < mpTypes.size());
 }
 
 AnimationNode::AnimationNode( const AnimationNode& rNode )