Error check using IsValid functions and return error unions (#191)

* Verify shaders are valid

* Verify images are valid

* Verify models are valid

* Verify materials are valid

* Verify textures are valid

* Verify render textures are valid

* Verify waves are valid

* Verify sounds are valid

* Verify music is valid

* Verify audio streams are valid

* Verify fonts are valid

* Update examples to handle error unions

examples/audio/raw_stream.zig

@@ -41,7 +41,7 @@ pub fn main() anyerror!void {
     rl.setAudioStreamBufferSizeDefault(MAX_SAMPLES_PER_UPDATE);
 
     // Init raw audio stream (sample rate: 44100, sample size: 16bit-short, channels: 1-mono)
-    const stream = rl.loadAudioStream(44100, 16, 1);
+    const stream = try rl.loadAudioStream(44100, 16, 1);
     defer rl.unloadAudioStream(stream); // Close raw audio stream and delete buffers from RAM
 
     rl.setAudioStreamCallback(stream, &audioInputCallback);

examples/shaders/texture_outline.zig

@@ -15,10 +15,10 @@ pub fn main() anyerror!void {
     rl.initWindow(screenWidth, screenHeight, "raylib [shaders] example - Apply an outline to a texture");
     defer rl.closeWindow(); // Close window and OpenGL context
 
-    const texture: rl.Texture = rl.Texture.init("resources/textures/fudesumi.png");
+    const texture: rl.Texture = try rl.Texture.init("resources/textures/fudesumi.png");
     defer rl.unloadTexture(texture);
 
-    const shdrOutline: rl.Shader = rl.loadShader(null, "resources/shaders/glsl330/outline.fs");
+    const shdrOutline: rl.Shader = try rl.loadShader(null, "resources/shaders/glsl330/outline.fs");
     defer rl.unloadShader(shdrOutline);
 
     var outlineSize: f32 = 2.0;

examples/textures/sprite_anim.zig

@@ -17,7 +17,7 @@ pub fn main() anyerror!void {
     defer rl.closeWindow(); // Close window and OpenGL context
 
     // NOTE: Textures MUST be loaded after Window initialization (OpenGL context is required)
-    const scarfy: rl.Texture = rl.Texture.init("resources/textures/scarfy.png"); // Texture loading
+    const scarfy: rl.Texture = try rl.Texture.init("resources/textures/scarfy.png"); // Texture loading
     defer rl.unloadTexture(scarfy); // Texture unloading
 
     const position = rl.Vector2.init(350.0, 280.0);

examples/textures/textures_background_scrolling.zig

@@ -20,9 +20,9 @@ pub fn main() anyerror!void {
 
     // NOTE: Be careful, background width must be equal or bigger than screen width
     // if not, texture should be draw more than two times for scrolling effect
-    const background = rl.loadTexture("resources/textures/cyberpunk_street_background.png");
-    const midground = rl.loadTexture("resources/textures/cyberpunk_street_midground.png");
-    const foreground = rl.loadTexture("resources/textures/cyberpunk_street_foreground.png");
+    const background = try rl.loadTexture("resources/textures/cyberpunk_street_background.png");
+    const midground = try rl.loadTexture("resources/textures/cyberpunk_street_midground.png");
+    const foreground = try rl.loadTexture("resources/textures/cyberpunk_street_foreground.png");
     defer rl.unloadTexture(background); // Unload background texture
     defer rl.unloadTexture(midground); // Unload midground texture
     defer rl.unloadTexture(foreground); // Unload foreground texture

examples/textures/textures_image_loading.zig

@@ -25,8 +25,8 @@ pub fn main() anyerror!void {
 
     // NOTE: Textures MUST be loaded after Window initialization (OpenGL context is required)
 
-    const image = rl.loadImage("logo/logo.png"); // Loaded in CPU memory (RAM)
-    const texture = rl.loadTextureFromImage(image); // Image converted to texture, GPU memory (VRAM)
+    const image = try rl.loadImage("logo/logo.png"); // Loaded in CPU memory (RAM)
+    const texture = try rl.loadTextureFromImage(image); // Image converted to texture, GPU memory (VRAM)
     // Once image has been converted to texture and uploaded to VRAM,
     // it can be unloaded from RAM
     rl.unloadImage(image);