diff --git a/apps/roofer-app/roofer-app.cpp b/apps/roofer-app/roofer-app.cpp
index 9bdcc76e..eef1566c 100644
--- a/apps/roofer-app/roofer-app.cpp
+++ b/apps/roofer-app/roofer-app.cpp
@@ -970,6 +970,7 @@ int main(int argc, const char* argv[]) {
         }
       }
       sorting_running.store(false);
+      sorted_pending.notify_one();
       logger.debug("[sorter] Finished sorter");
     });
 
diff --git a/src/extra/misc/Vector2DOpsGEOS.cpp b/src/extra/misc/Vector2DOpsGEOS.cpp
index c8d9fd9b..a413af2f 100644
--- a/src/extra/misc/Vector2DOpsGEOS.cpp
+++ b/src/extra/misc/Vector2DOpsGEOS.cpp
@@ -22,6 +22,7 @@
 #include <geos_c.h>
 #include <roofer/logger/logger.h>
 
+#include <__config>
 #include <roofer/misc/Vector2DOps.hpp>
 #include <vector>
 
@@ -48,6 +49,8 @@ namespace roofer::misc {
   }
   bool orient_polygon(GEOSGeometry*& g_polygon, ORIENTATION orientation) {
     const GEOSGeometry* g_ring = GEOSGetExteriorRing_r(gc, g_polygon);
+    if (g_ring == nullptr)
+      throw std::runtime_error("orient_polygon: unable to get exterior ring");
     GEOSGeometry* g_ring_ = orient_ring(g_ring, orientation);
     bool reversed = false;
     if (!g_ring_) {
@@ -212,19 +215,35 @@ namespace roofer::misc {
         to_geos_polygon(lr, g_polygon);
 
         if (GEOSisValid_r(gc, g_polygon) != 1) {
-          logger.info("feature not valid");
+          logger.error("Encouterend feature that is not valid. WKT: {}",
+                       GEOSGeomToWKT_r(gc, g_polygon));
           GEOSGeom_destroy_r(gc, g_polygon);
           // if (output_failures) polygons_out.push_back(lr);
-          continue;
+          throw std::runtime_error("feature not valid");
         }
 
         GEOSGeometry* simplified_geom =
             GEOSSimplify_r(gc, g_polygon, double(tolerance));
         if (GEOSisValid_r(gc, simplified_geom) != 1) {
-          logger.info("feature not valid after simplify");
+          logger.error(
+              "Encouterend feature that is not valid after simplify. WKT: {}",
+              GEOSGeomToWKT_r(gc, simplified_geom));
           GEOSGeom_destroy_r(gc, g_polygon);
+          GEOSGeom_destroy_r(gc, simplified_geom);
           // if (output_failures) polygons_out.push_back(lr);
-          continue;
+          throw std::runtime_error("feature not valid after simplify");
+        }
+        // dump simplified geometry to wkt
+        if (GEOSGetNumGeometries_r(gc, simplified_geom) != 1) {
+          logger.error(
+              "Encouterend feature that is a multi-geometry after simplify. "
+              "WKT: {}",
+              GEOSGeomToWKT_r(gc, simplified_geom));
+          GEOSGeom_destroy_r(gc, g_polygon);
+          GEOSGeom_destroy_r(gc, simplified_geom);
+          // if (output_failures) polygons_out.push_back(lr);
+          throw std::runtime_error(
+              "feature has multiple geometries after simplify");
         }
         if (orient_after_simplify) orient_polygon(simplified_geom, CCW);