additional cleanup: fixes the cleanup of NULL routines

lib.c

@@ -1207,12 +1207,16 @@ void ink_clean_routines(struct context* ctx) {
     null.type = INK_INTEGER;
     for(i = 0; i < ctx->routines_top; ++i) {
         if(ctx->routines[i].panic == INK_ROUTINE_CAN_REUSE || ctx->routines[i].panic == INK_ROUTINE_SUCCESS) {
-            for (j = 0; j < ctx->routines[i].top; ++j) {
-                ctx->routines[i].stack[j] = null;
+            if(ctx->routines[i].stack != NULL) {
+                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;
+            if(ctx->routines[i].function_stack != 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;