Oops, move assert back to shut the compiler up.

heatmap.c

@@ -156,15 +156,15 @@ unsigned char* heatmap_render_saturated_to(const heatmap_t* h, const heatmap_col
              */
             const float val = (*bufline > saturation ? saturation : *bufline)/saturation;
 
-            /* This is probably caused by a negative entry in the stamp! */
-            assert(val >= 0.0f);
-
             /* We add 0.5 in order to do real rounding, not just dropping the
              * decimal part. That way we are certain the highest value in the
              * colorscheme is actually used.
              */
             const size_t idx = (size_t)((float)(colorscheme->ncolors-1)*val + 0.5f);
 
+            /* This is probably caused by a negative entry in the stamp! */
+            assert(val >= 0.0f);
+
             /* This should never happen. It is likely a bug in this library. */
             assert(idx < colorscheme->ncolors);