Stdio.Buffer: Check for PIKE_T_FUNCTION before acting on objects.

src/modules/_Stdio/buffer.cmod

@@ -455,16 +455,14 @@ PIKECLASS Buffer
 
   PMOD_EXPORT void io_actually_trigger_output( Buffer *io )
   {
-    if (UNLIKELY(!io->output.u.object->prog)) {
-      /* Destructed object. */
-      free_svalue(&io->output);
-      SET_SVAL(io->output, PIKE_T_INT, NUMBER_NUMBER, integer, 0);
-      return;
-    }
+    if (io->output.tu.named_type == PIKE_T_FUNCTION) {
+      if (UNLIKELY(!io->output.u.object->prog)) {
+        /* Destructed object. */
+        free_svalue(&io->output);
+        return;
+      }
 
-    if ( io->output.u.object ) {
       move_svalue(Pike_sp++, &io->output);
-      SET_SVAL(io->output, PIKE_T_INT, NUMBER_NUMBER, integer, 0);
       apply_svalue(Pike_sp-1, 0);
       pop_n_elems(2);
     }
@@ -990,11 +988,8 @@ PIKECLASS Buffer
     if (f)
       assign_svalue(&io->output, f);
     else {
-      if (io->output.u.object) {
+      if (io->output.tu.named_type == PIKE_T_FUNCTION)
         free_svalue(&io->output);
-        io->output.u.object = 0;	// free_svalue() puts in -1
-      }
-      SET_SVAL(io->output, PIKE_T_INT, NUMBER_NUMBER, integer, 0);
     }
   }