set slider to -1 so we don't switch to 0 before the internalcalltree is ready

libs/remix-ui/debugger-ui/src/lib/slider/slider.tsx

@@ -9,6 +9,7 @@ export const Slider = ({ jumpTo, sliderValue, traceLength }) => {
   }, [sliderValue])
 
   const setValue = (value) => {
+    if (value < 0) return 
     if (value === slider.current.value) return
     slider.current.value = value
     if (onChangeId.current) {

libs/remix-ui/debugger-ui/src/lib/step-manager/step-manager.tsx

@@ -4,7 +4,7 @@ import ButtonNavigator from '../button-navigator/button-navigator' // eslint-dis
 
 export const StepManager = ({ stepManager: { jumpTo, traceLength, stepIntoBack, stepIntoForward, stepOverBack, stepOverForward, jumpOut, jumpNextBreakpoint, jumpPreviousBreakpoint, jumpToException, registerEvent } }) => {
   const [state, setState] = useState({
-    sliderValue: 0,
+    sliderValue: -1,
     revertWarning: '',
     stepState: '',
     jumpOutDisabled: true