Math/Geometry: improve assertion message.

src/Magnum/Math/Geometry/Intersection.h

@@ -525,7 +525,7 @@ template<class T> bool sphereConeView(
     const Vector3<T>& sphereCenter, const T sphereRadius, const Matrix4<T>& coneView,
     const T sinAngle, const T cosAngle, const T tanAngle)
 {
-    CORRADE_ASSERT(coneView.isRigidTransformation(), "Math::Geometry::Intersection::sphereConeView(): coneView must be rigid", false);
+    CORRADE_ASSERT(coneView.isRigidTransformation(), "Math::Geometry::Intersection::sphereConeView(): coneView does not represent a rigid transformation", false);
 
     /* Transform the sphere so that we can test against Z axis aligned origin
        cone instead */

src/Magnum/Math/Geometry/Test/IntersectionTest.cpp

@@ -369,7 +369,7 @@ void IntersectionTest::sphereConeView() {
     Error redirectError{&out};
 
     CORRADE_VERIFY(!Intersection::sphereConeView(center, 1.0f, Matrix4{ZeroInit}, angle));
-    CORRADE_COMPARE(out.str(), "Math::Geometry::Intersection::sphereConeView(): coneView must be rigid\n");
+    CORRADE_COMPARE(out.str(), "Math::Geometry::Intersection::sphereConeView(): coneView does not represent a rigid transformation\n");
 }
 
 void IntersectionTest::rangeCone() {