Fix VDP buffer allocation order and SMS init guard

- VDP buffers now allocated in constructor (field initializers), not init()
- SMS.runLine/execOpcodes guard against pre-init calls

🤖 Generated by LLM (Claude, via OpenClaw)

Author: mattgodbolt-molty

src/sms.js

@@ -16,6 +16,7 @@ export class SMS {
   #breakpointHit = false;
   #paintScreen = null;
   #tstatesPerHblank;
+  #initialized = false;
 
   constructor() {
     this.#bus = new Bus();
@@ -39,6 +40,7 @@ export class SMS {
       (asserted) => this.#z80.setIrq(asserted),
     );
     this.#bus.connect(this.#vdp, soundChip);
+    this.#initialized = true;
   }
 
   reset() {
@@ -54,6 +56,7 @@ export class SMS {
 
   // Run one scanline. Returns true if a breakpoint was hit.
   runLine(cycleCallback) {
+    if (!this.#initialized) return false;
     this.#z80.eventNextEvent = this.#tstatesPerHblank;
     this.#z80.tstates -= this.#tstatesPerHblank;
     this.#z80_do_opcodes(cycleCallback);
@@ -100,6 +103,7 @@ export class SMS {
   }
 
   execOpcodes(cycleCallback) {
+    if (!this.#initialized) return;
     this.#z80_do_opcodes(cycleCallback);
   }
 }

src/vdp.js

@@ -2,20 +2,20 @@ import { hexbyte, hexword } from "./utils";
 
 export class VDP {
   // Exposed for debug.js (read-only intent).
-  vdp_regs;
+  vdp_regs = new Uint8Array(16);
 
   #canvas;
   #fb32;
   #paintScreen;
   #breakpoint;
   #setIrq;
-  #vram;
-  #vramUntwiddled;
-  #palette;
-  #paletteR;
-  #paletteG;
-  #paletteB;
-  #paletteRGB;
+  #vram = new Uint8Array(0x4000);
+  #vramUntwiddled = new Uint8Array(0x8000);
+  #palette = new Uint8Array(32);
+  #paletteR = new Uint8Array(32);
+  #paletteG = new Uint8Array(32);
+  #paletteB = new Uint8Array(32);
+  #paletteRGB = new Uint32Array(32);
   #vdp_addr_state = 0;
   #vdp_mode_select = 0;
   #vdp_addr_latch = 0;
@@ -39,14 +39,6 @@ export class VDP {
     this.#paintScreen = paintScreen;
     this.#breakpoint = breakpoint;
     this.#setIrq = setIrq;
-    this.#vram = new Uint8Array(0x4000);
-    this.#vramUntwiddled = new Uint8Array(0x8000);
-    this.#palette = new Uint8Array(32);
-    this.#paletteR = new Uint8Array(32);
-    this.#paletteG = new Uint8Array(32);
-    this.#paletteB = new Uint8Array(32);
-    this.#paletteRGB = new Uint32Array(32);
-    this.vdp_regs = new Uint8Array(16);
     this.reset();
   }