Fixed rusty db not found (#743)

Co-authored-by: SamTV12345 <noreply+samtv1235@github.com>

databases/rusty_db.ts

@@ -1,8 +1,7 @@
 import AbstractDatabase from "../lib/AbstractDatabase";
-import {KeyValueDB} from "rusty-store-kv";
 
 export default class Rusty_db extends AbstractDatabase {
-    db: KeyValueDB | null | undefined
+    db: any | null | undefined
 
 
     constructor(settings: {filename: string}) {
@@ -35,7 +34,16 @@ export default class Rusty_db extends AbstractDatabase {
     }
 
     async init() {
-        this.db = new KeyValueDB(this.settings.filename!);
+        let RUSTY_DB
+        try {
+            RUSTY_DB = await import('rusty-store-kv');
+        } catch (err) {
+            throw new Error(
+                'better-sqlite3 not found. It was removed from ueberdb\'s dependencies because it requires ' +
+                'compilation which fails on several systems. If you still want to use sqlite, run ' +
+                '"npm install better-sqlite3" in your etherpad-lite ./src directory.');
+        }
+        this.db = new RUSTY_DB.KeyValueDB(this.settings.filename!);
     }
 
     close() {

databases/sqlite_db.ts

@@ -1,7 +1,6 @@
 'use strict';
 import {BulkObject} from "./cassandra_db";
 import AbstractDatabase, {Settings} from "../lib/AbstractDatabase";
-import SQLITEDB from "better-sqlite3";
 
 /**
  * 2011 Peter 'Pita' Martischka