[DataGrid] Log error if rowCount is used with client-side pagination

docs/data/data-grid/pagination/pagination.md

@@ -120,6 +120,11 @@ React.useEffect(() => {
 <DataGrid rowCount={rowCountState} />;
 ```
 
+:::warning
+The `rowCount` prop is used in server-side pagination mode to inform the DataGrid about the total number of rows in your dataset.
+This prop is ignored when the `paginationMode` is set to `client`, meaning the pagination is handled on the client-side.
+:::
+
 {{"demo": "ServerPaginationGrid.js", "bg": "inline"}}
 
 ### Cursor implementation

packages/x-data-grid/src/internals/utils/propValidation.ts

@@ -1,3 +1,4 @@
+import { isNumber } from '@mui/x-data-grid/utils/utils';
 import { DataGridProcessedProps } from '../../models/props/DataGridProps';
 
 export type PropValidator<TProps> = (props: TProps) => string | undefined;
@@ -13,6 +14,11 @@ export const propValidatorsDataGrid: PropValidator<DataGridProcessedProps>[] = [
         'Please remove one of these two props.',
       ].join('\n')) ||
     undefined,
+  (props) =>
+    (props.paginationMode === 'client' &&
+      isNumber(props.rowCount) &&
+      'MUI X: Usage of the `rowCount` prop with client side pagination (`paginationMode="client"`) has no effect. `rowCount` is only meant to be used with `paginationMode="server"`.') ||
+    undefined,
 ];
 
 const warnedOnceMap = new Set();