Fix T57578: Vertex Connect crash with less than two verts selected

source/blender/editors/mesh/editmesh_tools.c

@@ -1116,6 +1116,11 @@ static bool edbm_connect_vert_pair(BMEditMesh *em, wmOperator *op)
 	BMVert **verts;
 	bool checks_succeded = true;
 
+	/* sanity check */
+	if (verts_len < 2) {
+		return false;
+	}
+
 	verts = MEM_mallocN(sizeof(*verts) * verts_len, __func__);
 	{
 		BMIter iter;