Happily handle empty text messages (#6825)

This commig refactors the message-deletion modal and reuses it for case of removing
the entire message and trying to send it, which should trigger removal flow instead.

Fix vector-im/element-web#18873

src/components/views/rooms/EditMessageComposer.tsx

@@ -42,6 +42,7 @@ import ErrorDialog from "../dialogs/ErrorDialog";
 import QuestionDialog from "../dialogs/QuestionDialog";
 import { ActionPayload } from "../../../dispatcher/payloads";
 import AccessibleButton from '../elements/AccessibleButton';
+import { createRedactEventDialog } from '../dialogs/ConfirmRedactDialog';
 import SettingsStore from "../../../settings/SettingsStore";
 
 import { logger } from "matrix-js-sdk/src/logger";
@@ -331,6 +332,14 @@ export default class EditMessageComposer extends React.Component<IProps, IState>
 
         let shouldSend = true;
 
+        if (newContent?.body === '') {
+            this.cancelPreviousPendingEdit();
+            createRedactEventDialog({
+                mxEvent: editedEvent,
+            });
+            return;
+        }
+
         // If content is modified then send an updated event into the room
         if (this.isContentModified(newContent)) {
             const roomId = editedEvent.getRoomId();