Do not ignore '[[nodiscard]]` functions in example code

include/SFML/Graphics/Sprite.hpp

@@ -265,7 +265,10 @@ private:
 /// \code
 /// // Declare and load a texture
 /// sf::Texture texture;
-/// texture.loadFromFile("texture.png");
+/// if (!texture.loadFromFile("texture.png"))
+/// {
+///     // Handle error...
+/// }
 ///
 /// // Create a sprite
 /// sf::Sprite sprite(texture);

include/SFML/Graphics/Text.hpp

@@ -464,7 +464,10 @@ private:
 /// \code
 /// // Declare and load a font
 /// sf::Font font;
-/// font.loadFromFile("arial.ttf");
+/// if (!font.loadFromFile("arial.ttf"))
+/// {
+///     // Handle error...
+/// }
 ///
 /// // Create a text
 /// sf::Text text(font, "hello");

include/SFML/Graphics/Texture.hpp

@@ -120,8 +120,10 @@ public:
     /// This function is a shortcut for the following code:
     /// \code
     /// sf::Image image;
-    /// image.loadFromFile(filename);
-    /// texture.loadFromImage(image, area);
+    /// if (!image.loadFromFile(filename))
+    ///     return false;
+    /// if (!texture.loadFromImage(image, area))
+    ///     return false;
     /// \endcode
     ///
     /// The \a area argument can be used to load only a sub-rectangle
@@ -151,8 +153,10 @@ public:
     /// This function is a shortcut for the following code:
     /// \code
     /// sf::Image image;
-    /// image.loadFromMemory(data, size);
-    /// texture.loadFromImage(image, area);
+    /// if (!image.loadFromMemory(data, size))
+    ///     return false;
+    /// if (!texture.loadFromImage(image, area))
+    ///     return false;
     /// \endcode
     ///
     /// The \a area argument can be used to load only a sub-rectangle
@@ -183,8 +187,10 @@ public:
     /// This function is a shortcut for the following code:
     /// \code
     /// sf::Image image;
-    /// image.loadFromStream(stream);
-    /// texture.loadFromImage(image, area);
+    /// if (!image.loadFromStream(stream))
+    ///     return false;
+    /// if (!texture.loadFromImage(image, area))
+    ///     return false;
     /// \endcode
     ///
     /// The \a area argument can be used to load only a sub-rectangle