bug: fix empty texture detection logic

[XiYang6666]

resolve #1058

StartupEvents.registry("fluid", (event) => {
  event.create("test_fluid")
});

KubeJS/src/main/java/dev/latvian/mods/kubejs/generator/KubeAssetGenerator.java

Lines 25 to 27 in 21cd7e7

	default LoadedTexture loadTexture(ResourceLocation id) {
	return LoadedTexture.load(id);
	}

KubeJS/src/main/java/dev/latvian/mods/kubejs/client/LoadedTexture.java

Lines 24 to 48 in 21cd7e7

	public static LoadedTexture load(ResourceLocation id) {
	try {
	var path = KubeJSPaths.ASSETS.resolve(id.getNamespace() + "/textures/" + id.getPath() + ".png");
	if (Files.exists(path)) {
	try (var in = new BufferedInputStream(Files.newInputStream(path))) {
	var metaPath = KubeJSPaths.ASSETS.resolve(id.getNamespace() + "/textures/" + id.getPath() + ".png.mcmeta");
	return new LoadedTexture(ImageIO.read(in), Files.exists(metaPath) ? Files.readAllBytes(metaPath) : null);
	}
	} else if (id.getNamespace().equals(KubeJS.MOD_ID)) {
	var path1 = KubeJS.thisMod.getModInfo().getOwningFile().getFile().findResource("assets", "kubejs", "textures", id.getPath() + ".png");
	if (Files.exists(path1)) {
	try (var in = new BufferedInputStream(Files.newInputStream(path1))) {
	var metaPath = KubeJS.thisMod.getModInfo().getOwningFile().getFile().findResource("assets", "kubejs", "textures", id.getPath() + ".png.mcmeta");
	return new LoadedTexture(ImageIO.read(in), Files.exists(metaPath) ? Files.readAllBytes(metaPath) : null);
	}
	}
	}
	} catch (IOException e) {
	throw new RuntimeException(e);
	}
	return EMPTY;
	}

generator.loadTexture(...) always returns a non-null value
it uses LoadedTexture.EMPTY to represent an empty texture.