fix: Fix race condition on if EguiCtx is initialized before bones game (

#378)

Speculative fix for #377 (see for context)

It seems both the `setup_egui` and `step_bones_game` systems are gated
by if assets are loaded, which is an async process. My theory is that
assets finish loading after PreUpdate, before Update, so bones steps
without EguiCtx.

This prevents `step_bones_game` from being run until EguiCtx is inserted
in `setup_egui`. ~~Becaues `setup_egui` is gated by assets loaded,
`step_bones_game` is also implicitly gated by assets loaded. I only
check one `run_if` condition to avoid overhead executing systems that
make up the core game loop.~~

framework_crates/bones_bevy_renderer/src/lib.rs

@@ -28,7 +28,7 @@ use glam::*;
 
 use bevy_prototype_lyon::prelude as lyon;
 use bones_framework::prelude::{
-    self as bones, BitSet, ComponentIterBitset, SchemaBox, SCHEMA_REGISTRY,
+    self as bones, BitSet, ComponentIterBitset, EguiCtx, SchemaBox, SCHEMA_REGISTRY,
 };
 use prelude::convert::{IntoBevy, IntoBones};
 use serde::{de::Visitor, Deserialize, Serialize};
@@ -309,6 +309,7 @@ impl BonesBevyRenderer {
         .init_resource::<BonesGameEntity>();
 
         let assets_are_loaded = |data: Res<BonesData>| {
+            // Game is not required to have AssetServer, so default to true.
             data.asset_server
                 .as_ref()
                 .map(|x| x.load_progress.is_finished())
@@ -320,6 +321,8 @@ impl BonesBevyRenderer {
                 .map(|x| !x.load_progress.is_finished())
                 .unwrap_or(true)
         };
+        let egui_ctx_initialized =
+            |data: Res<BonesData>| data.game.shared_resource::<EguiCtx>().is_some();
 
         // Add the world sync systems
         app.add_systems(
@@ -350,7 +353,8 @@ impl BonesBevyRenderer {
                 ),
             )
                 .chain()
-                .run_if(assets_are_loaded),
+                .run_if(assets_are_loaded)
+                .run_if(egui_ctx_initialized),
         );
 
         if let Ok(render_app) = app.get_sub_app_mut(RenderApp) {