fix: fast-excel install error message

Author: yajra

src/Services/DataTable.php

@@ -489,7 +489,7 @@ protected function buildExcelFile()
         }
 
         if (! class_exists(ExcelServiceProvider::class)) {
-            throw new Exception('Please install maatwebsite/excel to be able to use this function.');
+            throw new Exception('Please composer require maatwebsite/excel to be able to use this function.');
         }
 
         if (! new $this->exportClass instanceof DataTablesExportHandler) {
@@ -783,9 +783,14 @@ public function fastExcelCallback(): Closure
 
     /**
      * @return \Rap2hpoutre\FastExcel\FastExcel
+     * @throws \Yajra\DataTables\Exceptions\Exception
      */
     protected function buildFastExcelFile(): FastExcel
     {
+        if (! class_exists(FastExcel::class)) {
+            throw new Exception('Please composer require rap2hpoutre/fast-excel to be able to use this function.');
+        }
+
         $query = null;
         if (method_exists($this, 'query')) {
             /** @var EloquentBuilder|QueryBuilder $query */