fix(client): refuse a truncated table in the multi-table upload

getdata now serves a selection over DC_MAXOBS_WEBEDIT / DC_MAXCELLS_WEBEDIT
truncated rather than aborting, which the EDIT screen reports above the grid. The
multi-table upload is the other caller: it fetches each table to compare the whole
of it against the uploaded workbook, so a partial read would compute the changes
against the wrong starting state and submit differences nobody asked for.

It now refuses such a table with a message naming the limit, rather than carrying
on with the rows it received. The EDIT screen already reads the same
sasparams.TRUNCATED flag; sas.service only transports the response.

client/src/app/multi-dataset/multi-dataset.component.ts

@@ -868,6 +868,21 @@ export class MultiDatasetComponent implements OnInit, AfterViewInit {
       return this.sasStoreService
         .callService(myParams, 'SASControlTable', 'editors/getdata', libds)
         .then((res: EditorsGetDataServiceResponse) => {
+          // getdata serves a selection over DC_MAXOBS_WEBEDIT / DC_MAXCELLS_WEBEDIT
+          // truncated, rather than aborting the way it used to. This flow compares
+          // the whole table against the upload, so a partial read would compute
+          // the changes against the wrong starting state - refuse the table
+          // instead of submitting differences nobody asked for.
+          const sasParams = res?.data?.sasparams?.[0]
+
+          if (sasParams && Number(sasParams.TRUNCATED) === 1) {
+            this.eventService.showInfoModal(
+              'Upload error',
+              `${libds} holds more than the EDIT limit allows (${sasParams.TRUNC_MSG}), so it cannot be compared with the upload. Raise DC_MAXOBS_WEBEDIT / DC_MAXCELLS_WEBEDIT, or submit the table without the multi-table upload.`
+            )
+            return undefined
+          }
+
           return res
         })
         .catch((err: any) => {