Crash when trying to create zero sized classid color map texture

[Wumpf]

Running rerun-io/grounding-sam@e1eb004 causes a wgpu error which causes a panic in release mode.

2023-04-20T14:22:44Z ERROR wgpu::backend::direct] Handling wgpu errors as fatal by default

thread 'ThreadId(1)' panicked at 'wgpu error: Validation Error

Caused by:
    In Device::create_texture
    Dimension Y is zero

', wgpu-0.15.1/src/backend/direct.rs:3024

   8: core::panicking::panic_fmt
             at core/src/panicking.rs:64:14`

Running it in debug isn't a crash but reveals that somewhere we create a zero sized color map:

[2023-04-20T15:08:46Z WARN  re_renderer::error_tracker] unknown error cause cause=InvalidDimension(Zero(Y))
[2023-04-20T15:08:46Z ERROR re_renderer::error_tracker] WGPU error tick_nr=85 description=Validation Error

    Caused by:
        In Device::create_texture
          note: label = `class_id_colormap`
        Dimension Y is zero