[MC-127478] Texture metadata parsing fails if animation block is not present

Behavior

When using a texture .mcmeta without an "animation" section, the parsing fails with an error (example below). The JSON is otherwise perfectly valid.

Error

[01:11:08] [Client thread/ERROR]: Unable to parse metadata from minecraft:textures/blocks/glass.png : com.google.gson.JsonSyntaxException: Missing animation, expected to find a JsonObject

Source (glass.png.mcmeta)

{
    "ctm": {
        "ctm_version": 1,
        "type": "CTM",
        "layer": "CUTOUT",
        "textures": [ "blocks/glass_ctm" ],
        "extra": { "connect_inside": true }
    }
}

Expected Behavior

The mcmeta is loaded normally, the animation section is skipped, and the texture just has no animation.