Streaming tables in Delta Live Tables (DLT) only support append-only operations in the SOURCE.

The error occurs because:

1. Your silver table uses SCD Type 1, which performs UPDATE and DELETE operations on existing records
2. Your gold table is defined as a streaming table, which only supports append-only operations
3. DLT detected non-append operations (MERGE operations from SCD Type 1) in the source silver table

Change your gold table from a streaming table to a materialized view.