Please help, when displaying the value of entity

[thoath2]

Hello,
I have already installed a number of well-functioning plotly graphs. I like them very much. The software is very powerful. Now I have a problem with which I can't find a solution. Chatgpt also only turns in circles.
I have the following graph configuration:

type: custom:plotly-graph
title: PV-Überschuss-Management
defaults:
  entity:
    show_value: true
  yaxes:
    yaxes: null
    fixedrange: true
    autorange: true
    side: left
    overlaying: "y"
    visible: true
    showgrid: true
hours_to_show: current_day
refresh_interval: 10
min_y_axis: -50
max_y_axis: 10000
entities:
  - entity: sensor.wp_hp1_inverter_power_consumption
    yaxis: y1
    name: |
      $ex {
            return (
                    "WP-Elektr. Leistg. "
                    + "<span style='font-size: 16px; color: rgb(70 130 180)'>" 
                    + ys[ys.length - 1].toFixed(0) 
                    +  " W   </span>"
                   )
          }
    showlegend: true
    statistic: mean
    filters:
      - map_y: "y < 0 ? 0 : (1 * y)"
    extend_to_present: false
    period: 5minute
    fill: null
    fillcolor: rgba(70, 130, 180, 0.5)
    line:
      color: rgba(70, 130, 180, 1)
      width: 2
  - entity: sensor.wp_emgr_power_consumption_setpoint
    yaxis: y1
    show_value: true
    name: Soll
    showlegend: true
    filters:
      - map_y: "y < 0 ? 0 : (1 * y)"
    extend_to_present: false
    fill: null
    fillcolor: rgba(0, 0, 205, 0.5)
    line:
      color: rgba(0, 0, 205, 1)
      width: 2
  - entity: sensor.wp_aussentemperatur
    yaxis: y2
    name: |
      $ex {
            return (
                    "Außen "
                    + "<span style='font-size: 16px; color: rgb(154 205 50)'>" 
                    + ys[ys.length - 1].toFixed(1) 
                    +  " °C</span>"
                   )
          }
    showlegend: true
    show_value: true
    statistic: mean
    filters:
      - map_y: "y < -50 ? null : (1 * y)"
    extend_to_present: false
    period: 5minute
    fill: null
    fillcolor: rgba(154, 205, 50, 0.5)
    line:
      color: rgba(154, 205, 50, 1)
      width: 2
layout:
  height: 600
  grid:
    rows: 2
    columns: 1
    roworder: top to bottom
  yaxis:
    title:
      text: W
  yaxis2:
    title:
      text: °C
  shapes:
    - type: line
      name: |
        $ex {
              var aktDate = new Date(); //Date.now();
              var aktHour = aktDate.getHours();
              var strAktHour = "0" + aktHour 
              strAktHour = strAktHour.substr(strAktHour.length - 2)
              var aktMinute = aktDate.getMinutes();
              var strAktMinute = "0" + aktMinute 
              strAktMinute = strAktMinute.substr(strAktMinute.length - 2)
              var strHM = strAktHour + ":" + strAktMinute
              return (
                      "Akt. Zeitpunkt "                    
                      + [strHM] + " "                   
                     )
            }
      showlegend: true
      x0: $ex Date.now()
      x1: $ex Date.now()
      y0: 0
      y1: 1
      xref: x
      yref: paper
      line:
        color: grey
        dash: dot
        width: 2

This works perfectly. The graph is displayed well. The last value is also displayed right of the line.

But when I change the "name"-configuration
from

  - entity: sensor.wp_emgr_power_consumption_setpoint
    yaxis: y1
    show_value: true
    name: Soll

to

  - entity: sensor.wp_emgr_power_consumption_setpoint
    yaxis: y1
    show_value: true
    name: |
      $ex {
            return (
                    "Soll (WP-El. Leistg.) "
                    + "<span style='font-size: 16px; color: rgb(0 0 205)'>" 
                    + ys[ys.length - 1].toFixed(1)
                    +  " W   </span>"
                   )
          }

there is an error "Error: at [entitsits.1name]: ys.length -1)]. Tofixed is not a function" -> See picture:

I have already tried everything, for example the test of "undefined" or "null"..., but it doesn't work. What can I do?

Thank You
Thomas