Fix unhandled enum warning

libs/geom/include/psemek/geom/sign.hpp

@@ -1,5 +1,7 @@
 #pragma once
 
+#include <psemek/util/assert.hpp>
+
 namespace psemek::geom
 {
 
@@ -31,6 +33,9 @@ namespace psemek::geom
 		case sign_t::zero: return sign_t::zero;
 		case sign_t::negative: return sign_t::positive;
 		}
+
+		assert(false);
+		return sign_t::zero;
 	}
 
 }