additional cleanup: removing function stack elements too

lib.c

@@ -1210,7 +1210,12 @@ void ink_clean_routines(struct context* ctx) {
             for (j = 0; j < ctx->routines[i].top; ++j) {
                 ctx->routines[i].stack[j] = null;
             }
+            for (j = 0; j < ctx->routines[i].function_stack_top; ++j) {
+                ctx->routines[i].function_stack[j].executing = null;
+                ctx->routines[i].function_stack[j].index = 0;
+            }
             ctx->routines[i].top = 0;
+            ctx->routines[i].function_stack_top = 0;
         }
     }
 }