Add assert for texture upload inside render pass on WebGPU (#8504)

Texture data upload during a render pass submits command buffers which
invalidates the active pass encoder. Add a debug assert in the WebGPU
uploadImmediate path to catch this early with a clear message pointing
to the fix.

Made-with: Cursor

Co-authored-by: Martin Valigursky <mvaligursky@snapchat.com>

Author: mvaligursky

src/platform/graphics/webgpu/webgpu-texture.js

@@ -327,6 +327,9 @@ class WebgpuTexture {
     uploadImmediate(device, texture) {
 
         if (texture._needsUpload || texture._needsMipmapsUpload) {
+            Debug.assert(!device.insideRenderPass,
+                `Texture.upload() for "${texture.name}" was called while inside a render pass, which is not currently supported. ` +
+                'Move texture updates to the before() or after() function of the RenderPass.');
             this.uploadData(device);
 
             texture._needsUpload = false;