Merge branch 'master' of http://176.104.105.124:3000/safet.purkovic/PDFEngineDemoUI

src/views/demoComponent/DemoComponent1.js

-import React, { lazy, useEffect, useState } from 'react';
+import React, { lazy, useState } from 'react';
 import {
     CBadge,
     CButton,

src/views/demoComponent/DemoComponent2.js

     CCallout
 } from '@coreui/react';
 import CIcon from '@coreui/icons-react';
-import PDFEngine from 'PDFEngine';
+//import PDFEngine from 'PDFEngine';
 
 import MainChartExample from '../charts/MainChartExample.js';
 const WidgetsDropdown = lazy(() => import('../widgets/WidgetsDropdown.js'))

src/views/demoComponent/DemoComponent9.js

         setMargins(event.target.value);
     }
 
+    const validateMargins = () => {
+        const array = (margins).split(",");
+        let allNums = true;
+        array.forEach(function (element) {if (isNaN(element)) {allNums = false; setMargins("");}});
+        if (array.length === 4 && (margins).split(",").length === 4 && allNums === true) {
+            return true;
+        } else {
+            return false;
+        }
+    }
+
     const exec = () => {
+        if (!validateMargins()) {
+            alert("Incorrect margin parameters");
+            return;
+        }
+
         const query = [];
         const arrayMargins = margins.split(',');
-        if(arrayMargins.length > 0){
-        query.push(`MarginTop=${arrayMargins[0]}`);
-        query.push(`MarginRight=${arrayMargins[1]}`);
-        query.push(`MarginBottom=${arrayMargins[2]}`);
-        query.push(`MarginLeft=${arrayMargins[3]}`);
+        if (arrayMargins.length > 0) {
+            query.push(`MarginTop=${arrayMargins[0]}`);
+            query.push(`MarginRight=${arrayMargins[1]}`);
+            query.push(`MarginBottom=${arrayMargins[2]}`);
+            query.push(`MarginLeft=${arrayMargins[3]}`);
         }
         query.push(`PaperFormatType=${paperFormat}`);
         const queryString = (query) ? `?${query.join('&')}` : '';