Improve error message

lib/sm83/codegen.ts

@@ -48,8 +48,7 @@ export const generateSSA_Copy = (alloc: RegAlloc, ssa: AbsInsnCopy): Array
         case LocType.REGISTER:
             if (isA(ssa.dest) && typeof ssa.source !== 'number' && ssa.source.type === LocType.VARIABLE) {
                 output.push(`LD A, (${ssa.source.name})`)
-
-                // TODO: Remove check with peephole optimizer
+                // TODO: Remove check later with peephole optimizer
             } else if (source !== ssa.dest.name) {
                 output.push(`LD ${ssa.dest.name}, ${source}`)
             }
@@ -57,8 +56,7 @@ export const generateSSA_Copy = (alloc: RegAlloc, ssa: AbsInsnCopy): Array
 
         case LocType.VARIABLE:
             if (source !== R8.A) {
-                console.log(source, ssa)
-                throw new Error("unsupported")
+                throw new Error(`can only deref address into A (had ${source})`)
             }
             output.push(`LD (${ssa.dest.name}), A`)
             break