add safety checks to attachments, to prevent out of bounds addressing if e.g. underlying assets changed

Editor/SkinAttachmentTargetEditor.cs

 			var checksumFailed = driver.CommitRequired();
 			if (checksumFailed)
 			{
-				EditorGUILayout.HelpBox("Rebuild required: Checksum of one or more subjects does not match checksum of data.", MessageType.Warning);
+				EditorGUILayout.HelpBox("Rebuild required: Checksum of driver or one or more subjects does not match checksum of data.", MessageType.Warning);
 			}
 			else if (driver.attachData.subjectCount != driver.subjects.Count)
 			{

Runtime/SkinAttachmentData.cs

 	[PreferBinarySerialization]
 	public class SkinAttachmentData : ScriptableObject
 	{
+		//[HideInInspector]
+		//public int driverChecksum = -1;
+		[HideInInspector]
+		public int driverVertexCount = 0;
+
 		[HideInInspector]
 		public ulong checksum0 = 0;
 		[HideInInspector]
 
 		public void Clear()
 		{
+			driverVertexCount = 0;
 			checksum0 = 0;
 			checksum1 = 0;
 			poseCount = 0;

Runtime/SkinAttachmentTarget.cs

 			Profiler.EndSample();
 		}
 
-		public ref MeshInfo GetCachedMeshInfo()
+		public ref MeshInfo GetCachedMeshInfo(bool forceRefresh = false)
-			if (frameIndex != cachedMeshInfoFrame)
+			if (frameIndex != cachedMeshInfoFrame || forceRefresh)
 			{
 				UpdateMeshInfo(ref cachedMeshInfo);
 
 			if (attachData == null)
 				return false;
 
+			if (meshBuffers.vertexCount < attachData.driverVertexCount)
+				return true;
+
 			for (int i = 0, n = subjects.Count; i != n; i++)
 			{
 				if (subjects[i].Checksum() != attachData.Checksum())
 			if (attachData == null)
 				return;
 
-			var meshInfo = GetCachedMeshInfo();
+			var meshInfo = GetCachedMeshInfo(forceRefresh: true);
+			attachData.driverVertexCount = meshInfo.meshBuffers.vertexCount;
 			{
 				subjects.RemoveAll(p => (p == null));
 
 
 										foreach (var j in subject.meshAdjacency.vertexVertices[i])
 										{
-											var targetDelta = targetPositions.val[j] - meshBuffers.vertexPositions[targetNode];
-											var targetNormalDist = Vector3.Dot(targetDelta, meshBuffers.vertexNormals[targetNode]);
+											var targetDelta = targetPositions.val[j] - meshInfo.meshBuffers.vertexPositions[targetNode];
+											var targetNormalDist = Vector3.Dot(targetDelta, meshInfo.meshBuffers.vertexNormals[targetNode]);
 											if (targetNormalDist < 0.0f)
 											{
 												var d = Vector3.SqrMagnitude(targetDelta);
 											rootGen.val[i] = -1;
 
 											// see if node qualifies as second choice root
-											var targetDelta = targetPositions.val[i] - meshBuffers.vertexPositions[targetNode];
-											var targetNormalDist = Mathf.Abs(Vector3.Dot(targetDelta, meshBuffers.vertexNormals[targetNode]));
+											var targetDelta = targetPositions.val[i] - meshInfo.meshBuffers.vertexPositions[targetNode];
+											var targetNormalDist = Mathf.Abs(Vector3.Dot(targetDelta, meshInfo.meshBuffers.vertexNormals[targetNode]));
 											if (targetNormalDist < bestDist0)
 											{
 												bestDist1 = bestDist0;
 								{
 									visitor.Ignore(bestVert0);
 									rootIdx.val[bestVert0] = bestNode0;
-									rootDir.val[bestVert0] = Vector3.Normalize(meshBuffers.vertexPositions[bestNode0] - targetPositions.val[bestVert0]);
+									rootDir.val[bestVert0] = Vector3.Normalize(meshInfo.meshBuffers.vertexPositions[bestNode0] - targetPositions.val[bestVert0]);
 									rootGen.val[bestVert0] = 0;
 									rootCount++;
 
 										rootIdx.val[bestVert1] = bestNode1;
-										rootDir.val[bestVert1] = Vector3.Normalize(meshBuffers.vertexPositions[bestNode1] - targetPositions.val[bestVert1]);
+										rootDir.val[bestVert1] = Vector3.Normalize(meshInfo.meshBuffers.vertexPositions[bestNode1] - targetPositions.val[bestVert1]);
 										rootGen.val[bestVert1] = 0;
 										rootCount++;
 									}
 			if (attachData == null)
 				return;
 
+			if (attachData.driverVertexCount > meshBuffers.vertexCount)
+				return;// prevent out of bounds if mesh shrunk since data was built
+
 			Profiler.BeginSample("resolve-subj-all");
 
 			subjects.RemoveAll(p => p == null);
 				int attachmentCount = subject.attachmentCount;
 				if (attachmentIndex == -1)
 					continue;
+
+				if (attachmentIndex + attachmentCount > attachData.itemCount)
+					continue;// prevent out of bounds if subject holds damaged index/count 
 
 				var indexPos = i * 2 + 0;
 				var indexNrm = i * 2 + 1;