Harden monitoring TG reanalyze reset

cmd/server/main.go

@@ -778,7 +778,13 @@ func (a *app) reanalyzeChannel(ctx context.Context, w http.ResponseWriter, r *ht
 		return
 	}
 	key := verdictKey(ch.Vertical)
-	tag, err := a.db.Exec(ctx, `UPDATE messages SET extracted = COALESCE(extracted, '{}'::jsonb) - $1 WHERE channel_id = $2`, key, id)
+	tag, err := a.db.Exec(ctx, `
+		UPDATE messages
+		SET extracted = (
+			CASE WHEN jsonb_typeof(extracted) = 'object' THEN extracted ELSE '{}'::jsonb END
+		) - $1
+		WHERE channel_id = $2
+	`, key, id)
 	if err != nil {
 		writeDBError(w, err)
 		return