fix a small bug with return values

compiler/src/main/kotlin/gay/pizza/pork/compiler/IrStubOpEmitter.kt

@@ -18,6 +18,7 @@ class IrStubOpEmitter(val irDefinition: IrDefinition, val code: CodeBuilder) : I
 
   fun final() {
     if (code.lastOp()?.op?.code != Opcode.Return) {
+      code.emit(Opcode.None)
       code.emit(Opcode.Return)
     }
   }

examples/bad.pork

@@ -1,5 +1,9 @@
 func depth(i: int32) {
+  if i <= 0 {
+    return None
+  }
   println("Depth: ", i)
+  depth(i - 1)
 }
 
 export func main() {
@@ -11,5 +15,19 @@ export func main() {
     true
   }
 
-  return println("uhm, bad")
+  if true {
+
+  } else {
+
+  }
+
+  if false {
+
+  } else {
+
+  }
+
+  depth(500)
+
+  println("uhm, bad")
 }