fix for ngOnDestroy throws error when in SSR - resolves #163 (#263)

fix for ngOnDestroy throws error when in SSR - resolves #163

Author: vlio20

CHANGELOG.md

@@ -14,6 +14,7 @@ All notable changes to this project will be documented in this file.
 - Stop using getters in template ([3858dde](https://github.com/vlio20/angular-datepicker/commit/3858dde)) closes [#239](https://github.com/vlio20/angular-datepicker/issues/239)
 
 ### Bug Fixed
+- fix for `ngOnDestroy` throws error when in SSR ([???](https://github.com/vlio20/angular-datepicker/commit/???)) closes [#163](https://github.com/vlio20/angular-datepicker/issues/163)
 - `displayDate` on the directive bug fix ([984aab8](https://github.com/vlio20/angular-datepicker/commit/984aab8)) closes [#254](https://github.com/vlio20/angular-datepicker/issues/254)
 - `max`/`min` date support for strings ([ad98d1b](https://github.com/vlio20/angular-datepicker/commit/ad98d1b)) closes [#250](https://github.com/vlio20/angular-datepicker/issues/250)
 - `value.split` is not a function bug fix ([38f6ce2](https://github.com/vlio20/angular-datepicker/commit/38f6ce2)) closes [#225](https://github.com/vlio20/angular-datepicker/issues/245)

src/app/date-picker/date-picker.component.ts

@@ -427,6 +427,9 @@ export class DatePickerComponent implements OnChanges,
 
   ngOnDestroy() {
     this.handleInnerElementClickUnlisteners.forEach(ul => ul());
-    this.appendToElement.removeChild(this.calendarWrapper);
+
+    if (this.appendToElement) {
+      this.appendToElement.removeChild(this.calendarWrapper);
+    }
   }
 }