fixes

lib/snippets/database/index.ts

@@ -2,6 +2,6 @@ import { Snippet } from '../../Snippet';
 
 export default class Database implements Snippet {
   public start (): Promise<void> {
-    // noop
+    return new Promise ((res) => res ());
   }
 }

lib/snippets/database/patch_actions/RenameColumn.ts

@@ -36,7 +36,18 @@ export class RenameColumn implements Serializable, PatchAction {
 
   public apply (db: Database): void {
     const table = db.get_table (this.table);
-    const column = table?.get_column(this.column);
-    column?.name = this.new_name;
+    if (typeof table === 'undefined' || table === null) {
+      throw new Error (
+        `table ${this.table} not found`
+      );
+    }
+    const column = table.get_column (this.column);
+    if (typeof column === 'undefined' || column === null) {
+      throw new Error (
+        `column ${this.column} not found in table ${this.table}`
+      );
+    }
+
+    column.name = this.new_name;
   }
 }