notcurses-input: flip for ncpp::render inversion

src/input/input.cpp

@@ -190,7 +190,7 @@ void Tick(ncpp::NotCurses* nc, uint64_t sec) {
   if(ncplot_add_sample(plot, sec, 0)){
     throw std::runtime_error("couldn't register timetick");
   }
-  if(!nc->render()){
+  if(nc->render()){
     throw std::runtime_error("error rendering");
   }
 }
@@ -232,7 +232,9 @@ int main(void){
   }
   n->styles_set(CellStyle::None);
   n->set_bg_default();
-  nc.render();
+  if(nc.render()){
+    throw std::runtime_error("error rendering");
+  }
   int y = 2;
   std::deque<wchar_t> cells;
   char32_t r;
@@ -289,9 +291,9 @@ int main(void){
       mtx.unlock();
       break;
     }
-    if(!nc.render()){
+    if(nc.render()){
       mtx.unlock();
-      break;
+      throw std::runtime_error("error rendering");
     }
     mtx.unlock();
     if(++y >= dimy - PLOTHEIGHT){ // leave six lines free on the bottom...