feat: remove guard condition

Memola/Canvas/Contexts/GraphicContext.swift

@@ -174,9 +174,6 @@ extension GraphicContext {
 
 extension GraphicContext: Drawable {
     func prepare(device: MTLDevice) {
-        guard vertexBuffer == nil else {
-            return
-        }
         vertexCount = vertices.count
         vertexBuffer = device.makeBuffer(bytes: vertices, length: vertexCount * MemoryLayout<ViewPortVertex>.stride, options: [])
     }

Memola/Canvas/Contexts/GridContext.swift

@@ -30,9 +30,6 @@ class GridContext {
 
 extension GridContext: Drawable {
     func prepare(device: MTLDevice) {
-        guard vertexBuffer == nil else {
-            return
-        }
         vertexBuffer = device.makeBuffer(bytes: vertices, length: vertexCount * MemoryLayout<GridVertex>.stride, options: [])
     }
 

Memola/Canvas/Contexts/ViewPortContext.swift

@@ -36,9 +36,6 @@ class ViewPortContext {
 
 extension ViewPortContext: Drawable {
     func prepare(device: MTLDevice) {
-        guard vertexBuffer == nil else {
-            return
-        }
         vertexBuffer = device.makeBuffer(bytes: vertices, length: vertexCount * MemoryLayout<ViewPortVertex>.stride, options: [])
     }