error TS2722: Cannot invoke an object which is possibly 'undefined'

Question

Description

IN angular 10, below is my ts-config.

{
  "compileOnSave": false,
  "compilerOptions": {
    "baseUrl": "./",
    "outDir": "./dist/out-tsc",
    "forceConsistentCasingInFileNames": true,
    "strict": true,
    "noImplicitReturns": true,
    "noFallthroughCasesInSwitch": true,
    "sourceMap": true,
    "declaration": false,
    "downlevelIteration": true,
    "experimentalDecorators": true,
    "moduleResolution": "node",
    "importHelpers": true,
    "target": "es2015",
    "module": "es2020",
    "lib": [
      "es2018",
      "dom"
    ]
  },
  "angularCompilerOptions": {
    "strictInjectionParameters": true,
    "strictTemplates": true
  }
}

when i try to serve my application i am facing below issue:

    ERROR in src/app/app.component.ts:8:14 - error TS2722: Cannot invoke an object which is possibly 'undefined'.

    8      <button (created)="oncreate($event)" ejs-button>Button</button>

But when i set strict:false it works fine.

Minimal Reproduction

1. download sample from below link strict mode sample.zip
2. Give npm i then ng serve

Exception or Error

D:\incidents\strict mode sample>ng serve
'wmic.exe' is not recognized as an internal or external command,
operable program or batch file.
(node:17616) ExperimentalWarning: The fs.promises API is experimental
Compiling @angular/core : es2015 as esm2015
Compiling @angular/animations : es2015 as esm2015
Compiling @angular/compiler/testing : es2015 as esm2015
Compiling @angular/animations/browser : es2015 as esm2015
Compiling @angular/common : es2015 as esm2015
Compiling @angular/core/testing : es2015 as esm2015
Compiling @angular/platform-browser : es2015 as esm2015
Compiling @angular/common/http : es2015 as esm2015
Compiling @angular/common/testing : es2015 as esm2015
Compiling @angular/platform-browser-dynamic : es2015 as esm2015
Compiling @angular/platform-browser/testing : es2015 as esm2015
Compiling @angular/router : es2015 as esm2015
Compiling @angular/forms : es2015 as esm2015
Compiling @angular/animations/browser/testing : es2015 as esm2015
Compiling @angular/common/http/testing : es2015 as esm2015
Compiling @angular/platform-browser/animations : es2015 as esm2015
Compiling @angular/platform-browser-dynamic/testing : es2015 as esm2015
Compiling @angular/router/testing : es2015 as esm2015
Compiling @syncfusion/ej2-angular-buttons : es2015 as esm2015
Compiling @syncfusion/ej2-angular-grids : es2015 as esm2015

chunk {main} main.js, main.js.map (main) 2 kB [initial] [rendered]
chunk {polyfills} polyfills.js, polyfills.js.map (polyfills) 677 bytes [initial] [rendered]
chunk {runtime} runtime.js, runtime.js.map (runtime) 6.15 kB [entry] [rendered]
chunk {styles} styles.js, styles.js.map (styles) 15 MB [initial] [rendered]
chunk {vendor} vendor.js, vendor.js.map (vendor) 341 kB [initial] [rendered]
Date: 2020-08-04T10:45:29.294Z - Hash: d04b0cca85382beb066d - Time: 29909ms

ERROR in src/app/app.component.ts:8:14 - error TS2722: Cannot invoke an object which is possibly 'undefined'.

8      <button (created)="oncreate($event)" ejs-button>Button</button>

Your Environment

"@angular/animations": "~10.0.6",
    "@angular/common": "~10.0.6",
    "@angular/compiler": "~10.0.6",
    "@angular/core": "~10.0.6",
    "@angular/forms": "~10.0.6",
    "@angular/platform-browser": "~10.0.6",
    "@angular/platform-browser-dynamic": "~10.0.6",
"@angular-devkit/build-angular": "~0.1000.5",
    "@angular/cli": "~10.0.5",
    "@angular/compiler-cli": "~10.0.6",

Suggestions from angular team,

https://github.com/angular/angular/issues/38342#issuecomment-668753033

anyone please suggest me, how to replace typedef of my events line of 82

I am registering events as they mentioned,