window.Chart is not a constructor - error in LWC

I created a LWC chart and for whatever reason I have this error.. but only for some records and I don't know why.
import { api, LightningElement, track } from 'lwc'; import chartJS from '@salesforce/resourceUrl/chart'; import { loadScript } from 'lightning/platformResourceLoader'; import getChartDetail from '@salesforce/apex/RenderChart.getChartDetail'; import { ShowToastEvent } from "lightning/platformShowToastEvent"; export default class myRadarChart extends LightningElement { @api recordId; @track chartData = []; @track chartLabel = []; getRandomColor() { var letters = '0123456789ABCDEF'; var color = '#'; for (var i = 0; i < 6; i++) { color += letters[Math.floor(Math.random() * 16)]; return color; connectedCallback(){ loadScript(this, chartJS + "/Chart.min.js") .then(() => { .catch((error) => { console.log("Error:", error); getChartDetail({ oppId : this.recordId }).then(result => { var tempresult = JSON.parse(JSON.stringify(result)); this.chartLabel = ["Power","Collaborate","CRTA","Pain","Value","Vision"]; this.chartData = []; for(let temp of tempresult){ let color = this.getRandomColor(); let tempdata = []; tempdata.push(temp.Power_no_concat__c); tempdata.push(temp.Collaborate_no_concat__c); tempdata.push(temp.Compelling_Reason_to_Act_CRTA_no_concat__c); tempdata.push(temp.Pain_no_concat__c); tempdata.push(temp.Value_no_concat__c); tempdata.push(temp.Vision_no_concat__c); let chartMap = { label: temp.Name, borderColor: color, fill: false, pointHoverBackgroundColor: color, backgroundColor: "rgba(255,255,255, 0)", data: tempdata this.chartData.push(chartMap); this.callRadarChart(); }).catch(error => { console.error('Error in RenderChart.getChartDetail' + error); this.dispatchEvent(new ShowToastEvent({ title: "Error", message: error, variant: "error", mode: "dismissable" callRadarChart(){ let config = { type: 'radar', data: { labels: this.chartLabel, datasets: this.chartData options:{ legend: { display: true, position: 'right', align: 'center', labels: { usePointStyle: true, this.insertToDOM("div.radarChart",config); insertToDOM(divclass,config) { const canvas = document.createElement("canvas"); const chartNode = this.template.querySelector(divclass); chartNode.innerHTML = ""; chartNode.appendChild(canvas); const ctx = canvas.getContext("2d"); this.chart = new window.Chart(ctx, config);

apex class:

public with sharing class RenderChart { @AuraEnabled(cacheable=true) public static List<Sales_Check__c> getChartDetail(String oppId) { Map<String,Decimal> mapnumberfields = new Map<String,Decimal>(); List<Sales_Check__c> salesCheckList = [SELECT Id, Name,Collaborate_no_concat__c, Compelling_Reason_to_Act_CRTA_no_concat__c, Pain_no_concat__c, Value_no_concat__c, Vision_no_concat__c, Power_no_concat__c FROM Sales_Check__c Where Opportunity__c =:oppId]; return salesCheckList;

This is the error i'm getting it:

Why i'm getting this error?