Report init errors to DuckDB via SetError

Previously, exceptions during extension initialization were
silently swallowed. Now the caught exception message is passed
to SetError so DuckDB can surface the actual error.

Author: Giorgi

DuckDB.ExtensionKit.Generators/ExtensionEntryPointGenerator.cs

@@ -125,8 +125,9 @@ public static byte Init(nint info, DuckDBExtensionAccess* access)
             Api.duckdb_disconnect(&connection);
             return 1;
         }}
-        catch (System.Exception)
+        catch (System.Exception ex)
         {{
+            SetError(access, info, ex.Message);
             return 0;
         }}
     }}