The general settings button doesn't work

On Firefox the general settings button throws an error when clicked.

ERROR TypeError: this.dialog.nativeElement.showModal is not a function Stack trace: GeneralSettingsButtonComponent.prototype.open@webpack-internal:///./src/components/general-settings-button/general-settings-button.component.ts:27:9 View_GeneralSettingsButtonComponent_0/<@ng:///AppModule/GeneralSettingsButtonComponent.ngfactory.js:13:23 handleEvent@webpack-internal:///./node_modules/@angular/core/fesm5/core.js:11387:16 callWithDebugContext@webpack-internal:///./node_modules/@angular/core/fesm5/core.js:12484:22 debugHandleEvent@webpack-internal:///./node_modules/@angular/core/fesm5/core.js:12187:12 dispatchEvent@webpack-internal:///./node_modules/@angular/core/fesm5/core.js:8854:16 renderEventHandlerClosure/<@webpack-internal:///./node_modules/@angular/core/fesm5/core.js:9298:38 decoratePreventDefault/<@webpack-internal:///./node_modules/@angular/platform-browser/fesm5/platform-browser.js:1200:36 ZoneDelegate.prototype.invokeTask@webpack-internal:///./node_modules/zone.js/dist/zone.js:421:17 onInvokeTask@webpack-internal:///./node_modules/@angular/core/fesm5/core.js:4334:24 ZoneDelegate.prototype.invokeTask@webpack-internal:///./node_modules/zone.js/dist/zone.js:420:17 Zone.prototype.runTask@webpack-internal:///./node_modules/zone.js/dist/zone.js:188:28 ZoneTask.invokeTask@webpack-internal:///./node_modules/zone.js/dist/zone.js:496:24 invokeTask@webpack-internal:///./node_modules/zone.js/dist/zone.js:1540:9 globalZoneAwareCallback@webpack-internal:///./node_modules/zone.js/dist/zone.js:1566:17 GeneralSettingsButtonComponent.html:1