bug in DiffRenderContext

It is triggered by user code, but I think the bug in how diff is rendered. If I use access.transition the failure is silent. access.syncTransition makes the issue clear.

[info] scala.MatchError: 3 (of class java.lang.Byte)
[info]  at levsha.impl.DiffRenderContext.deleteLoop(DiffRenderContext.scala:408)
[info]  at levsha.impl.DiffRenderContext.diff(DiffRenderContext.scala:242)
[info]  at korolev.internal.ApplicationInstance.$anonfun$onState$8(ApplicationInstance.scala:119)
[info]  at korolev.internal.ApplicationInstance.$anonfun$onState$8$adapted(ApplicationInstance.scala:119)
[info]  at korolev.internal.Frontend.$anonfun$performDomChanges$1(Frontend.scala:189)
[info]  at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.scala:18)
[info]  at korolev.effect.Effect$FutureEffect.delay(Effect.scala:78)
[info]  at korolev.effect.Effect$FutureEffect.delay(Effect.scala:66)
[info]  at korolev.internal.Frontend.performDomChanges(Frontend.scala:187)
[info]  at korolev.internal.ApplicationInstance.$anonfun$onState$7(ApplicationInstance.scala:119)
[info]  at scala.concurrent.impl.Promise$Transformation.run(Promise.scala:434)
[info]  at korolev.effect.Effect$FutureEffect$$anon$1.execute(Effect.scala:69)
[info]  at scala.concurrent.impl.Promise$Transformation.submitWithValue(Promise.scala:393)
[info]  at scala.concurrent.impl.Promise$DefaultPromise.submitWithValue(Promise.scala:302)
[info]  at scala.concurrent.impl.Promise$DefaultPromise.dispatchOrAddCallbacks(Promise.scala:276)
[info]  at scala.concurrent.impl.Promise$DefaultPromise.flatMap(Promise.scala:140)
[info]  at korolev.effect.Effect$FutureEffect.flatMap(Effect.scala:86)
[info]  at korolev.effect.Effect$FutureEffect.flatMap(Effect.scala:66)
[info]  at korolev.effect.syntax$EffectOps.flatMap(syntax.scala:36)
[info]  at korolev.internal.ApplicationInstance.$anonfun$onState$5(ApplicationInstance.scala:108)
[info]  at scala.concurrent.impl.Promise$Transformation.run(Promise.scala:434)
[info]  at korolev.effect.Effect$FutureEffect$$anon$1.execute(Effect.scala:69)
[info]  at scala.concurrent.impl.Promise$Transformation.submitWithValue(Promise.scala:393)
[info]  at scala.concurrent.impl.Promise$DefaultPromise.submitWithValue(Promise.scala:302)
[info]  at scala.concurrent.impl.Promise$DefaultPromise.dispatchOrAddCallbacks(Promise.scala:276)
[info]  at scala.concurrent.impl.Promise$DefaultPromise.flatMap(Promise.scala:140)
[info]  at korolev.effect.Effect$FutureEffect.flatMap(Effect.scala:86)
[info]  at korolev.effect.Effect$FutureEffect.flatMap(Effect.scala:66)
[info]  at korolev.effect.syntax$EffectOps.flatMap(syntax.scala:36)
[info]  at korolev.internal.ApplicationInstance.$anonfun$onState$1(ApplicationInstance.scala:105)
[info]  at scala.concurrent.impl.Promise$Transformation.run(Promise.scala:434)
[info]  at korolev.effect.Effect$FutureEffect$$anon$1.execute(Effect.scala:69)
[info]  at scala.concurrent.impl.Promise$Transformation.submitWithValue(Promise.scala:393)
[info]  at scala.concurrent.impl.Promise$DefaultPromise.submitWithValue(Promise.scala:302)
[info]  at scala.concurrent.impl.Promise$DefaultPromise.dispatchOrAddCallbacks(Promise.scala:276)
[info]  at scala.concurrent.impl.Promise$DefaultPromise.flatMap(Promise.scala:140)
[info]  at korolev.effect.Effect$FutureEffect.flatMap(Effect.scala:86)
[info]  at korolev.effect.Effect$FutureEffect.flatMap(Effect.scala:66)
[info]  at korolev.effect.syntax$EffectOps.flatMap(syntax.scala:36)
[info]  at korolev.internal.ApplicationInstance.onState(ApplicationInstance.scala:103)
[info]  at korolev.internal.ApplicationInstance.$anonfun$topLevelComponentInstance$2(ApplicationInstance.scala:84)
[info]  at korolev.internal.ComponentInstance.$anonfun$applyTransition$4(ComponentInstance.scala:280)
[info]  at scala.concurrent.impl.Promise$Transformation.run(Promise.scala:434)
[info]  at korolev.effect.Effect$FutureEffect$$anon$1.execute(Effect.scala:69)
[info]  at scala.concurrent.impl.Promise$Transformation.submitWithValue(Promise.scala:393)
[info]  at scala.concurrent.impl.Promise$DefaultPromise.submitWithValue(Promise.scala:302)
[info]  at scala.concurrent.impl.Promise$DefaultPromise.dispatchOrAddCallbacks(Promise.scala:276)
[info]  at scala.concurrent.impl.Promise$DefaultPromise.flatMap(Promise.scala:140)
[info]  at korolev.effect.Effect$FutureEffect.flatMap(Effect.scala:86)
[info]  at korolev.effect.Effect$FutureEffect.flatMap(Effect.scala:66)
[info]  at korolev.effect.syntax$EffectOps.flatMap(syntax.scala:36)
[info]  at korolev.internal.ComponentInstance.$anonfun$applyTransition$2(ComponentInstance.scala:279)
[info]  at scala.concurrent.impl.Promise$Transformation.run(Promise.scala:434)
[info]  at korolev.effect.Effect$FutureEffect$$anon$1.execute(Effect.scala:69)
[info]  at scala.concurrent.impl.Promise$Transformation.submitWithValue(Promise.scala:393)
[info]  at scala.concurrent.impl.Promise$DefaultPromise.submitWithValue(Promise.scala:302)
[info]  at scala.concurrent.impl.Promise$DefaultPromise.dispatchOrAddCallbacks(Promise.scala:276)
[info]  at scala.concurrent.impl.Promise$DefaultPromise.flatMap(Promise.scala:140)
[info]  at korolev.effect.Effect$FutureEffect.flatMap(Effect.scala:86)
[info]  at korolev.effect.Effect$FutureEffect.flatMap(Effect.scala:66)
[info]  at korolev.effect.syntax$EffectOps.flatMap(syntax.scala:36)
[info]  at korolev.internal.ComponentInstance.$anonfun$applyTransition$1(ComponentInstance.scala:277)
[info]  at korolev.internal.ComponentInstance.applyTransition(ComponentInstance.scala:282)
[info]  at korolev.internal.ComponentInstance$browserAccess$.syncTransition(ComponentInstance.scala:140)
[info]  at com.nt.front.UiWebService.$anonfun$config$433(UiWebService.scala:2793)

[fomkin]

The problem was partially fixed in Levsha 1.0.0. Now if tag content couldn’t be sorted during optimization it will be leaved unoptimized. However you can force optimization for these cases if you want. See optimizer options.

[fomkin]

It’s known problem. If levsha.macros.unableToSortTagWarnings sys property is true, you will get warning about this. Unfortunately I never added it to documentation. Try:

select(id := "dropdown-list",
  option(value := "choice1", if (true) selected else void, "Cat"),
  option(value := "choice2", if (false) selected else void, "Dog"),
  selectorId
)

Also you can use when as shortcut for if (cond) node else void.