The Echo Crystal item requires a texture file at this location:
src/main/resources/assets/echogates/textures/item/echo_crystal.png

The texture should be a 16x16 PNG image.

You can:
1. Create your own texture using an image editor
2. Use an AI tool to generate one
3. Find a free texture online (respecting licenses)
4. Use a placeholder texture temporarily

For a quick placeholder, you could copy the echo_shard.png from Minecraft's assets
or create a simple colored square in any image editor.
