Bug fix #34436

Two example files that crashed texture nodes. 
- On delete texture nodes, it should free the exec cache (because this cache
  stores the node pointer.
- On redo, nodes can exist can exist without typeinfo set. Exec (free) code
  was not checking for that. Don't ask me why this happens... tex nodes are weird.

source/blender/blenkernel/intern/node.c

@@ -991,6 +991,12 @@ void nodeFreeNode(bNodeTree *ntree, bNode *node)
 
 		if (treetype->free_node_cache)
 			treetype->free_node_cache(ntree, node);
+		
+		/* texture node has bad habit of keeping exec data around */
+		if (ntree->type == NTREE_TEXTURE && ntree->execdata) {
+			ntreeTexEndExecTree(ntree->execdata, 1);
+			ntree->execdata = NULL;
+		}
 	}
 	
 	/* since it is called while free database, node->id is undefined */
@@ -1040,6 +1046,7 @@ void ntreeFreeTree_ex(bNodeTree *ntree, const short do_id_user)
 				break;
 			case NTREE_TEXTURE:
 				ntreeTexEndExecTree(ntree->execdata, 1);
+				ntree->execdata = NULL;
 				break;
 		}
 	}

source/blender/nodes/intern/node_exec.c

@@ -248,8 +248,9 @@ void ntree_exec_end(bNodeTreeExec *exec)
 		MEM_freeN(exec->stack);
 	
 	for (n=0, nodeexec= exec->nodeexec; n < exec->totnodes; ++n, ++nodeexec) {
-		if (nodeexec->node->typeinfo->freeexecfunc)
-			nodeexec->node->typeinfo->freeexecfunc(nodeexec->node, nodeexec->data);
+		if (nodeexec->node->typeinfo)
+			if (nodeexec->node->typeinfo->freeexecfunc)
+				nodeexec->node->typeinfo->freeexecfunc(nodeexec->node, nodeexec->data);
 	}
 	
 	if (exec->nodeexec)