refactor: clean up

Memola/Canvas/Contexts/GraphicContext.swift

@@ -29,7 +29,7 @@ final class GraphicContext: @unchecked Sendable {
 
     var erasers: [URL: EraserStroke] = [:]
 
-    let concurrentQueue = DispatchQueue(label: "com.dispatchBarrier", attributes: .concurrent)
+    let barrierQueue = DispatchQueue(label: "com.memola.app.graphic-context", attributes: .concurrent)
 
     init() {
         setViewPortVertices()

Memola/Canvas/Geometries/Stroke/Strokes/PenStroke.swift

@@ -84,7 +84,7 @@ final class PenStroke: Stroke, @unchecked Sendable {
         eraserStrokes = Set(object.erasers.compactMap { [graphicContext] eraser -> EraserStroke? in
             guard let eraser = eraser as? EraserObject else { return nil }
             let url = eraser.objectID.uriRepresentation()
-            return graphicContext.concurrentQueue.sync(flags: .barrier) {
+            return graphicContext.barrierQueue.sync(flags: .barrier) {
                 if graphicContext.erasers[url] == nil {
                     let _stroke = EraserStroke(object: eraser)
                     _stroke.loadQuads(from: eraser)

Memola/Canvas/RenderPasses/GraphicRenderPass.swift

@@ -100,5 +100,18 @@ class GraphicRenderPass: RenderPass {
             }
             graphicContext.previousStroke = nil
         }
+
+        let eraserStrokes = graphicContext.eraserStrokes
+        for eraserStroke in eraserStrokes {
+            if eraserStroke.finishesSaving {
+                graphicContext.eraserStrokes.remove(eraserStroke)
+                continue
+            }
+            descriptor.colorAttachments[0].loadAction = clearsTexture ? .clear : .load
+            clearsTexture = false
+            eraserRenderPass.stroke = eraserStroke
+            eraserRenderPass.descriptor = descriptor
+            eraserRenderPass.draw(on: canvas, with: renderer)
+        }
     }
 }