add a *ignore* method to Promise to make tslint happy

preload.js

@@ -472,3 +472,9 @@ window.lokiFeatureFlags = {
   multiDeviceUnpairing: true,
   privateGroupChats: false,
 };
+
+// eslint-disable-next-line no-extend-native,func-names
+Promise.prototype.ignore = function() {
+  // eslint-disable-next-line more/no-then
+  this.then(() => {});
+};

ts/components/session/RegistrationTabs.tsx

@@ -235,7 +235,7 @@ export class RegistrationTabs extends React.Component<Props, State> {
       <SessionButton
         onClick={() => {
           if (signUpMode === SignUpMode.Default) {
-            void this.onSignUpGenerateSessionIDClick();
+            this.onSignUpGenerateSessionIDClick().ignore();
           } else {
             this.onSignUpGetStartedClick();
           }
@@ -417,7 +417,7 @@ export class RegistrationTabs extends React.Component<Props, State> {
     return (
       <SessionButton
         onClick={() => {
-          void this.register('english');
+          this.register('english').ignore();
         }}
         buttonType={SessionButtonType.FullGreen}
         text={this.props.i18n('continueYourSession')}

ts/global.d.ts

@@ -11,3 +11,7 @@ interface Window {
   setPassword: any;
   textsecure: any;
 }
+
+interface Promise<T> {
+  ignore(): void;
+}