Fix unit test

tests/process_error_test.php

@@ -110,11 +110,10 @@ public function test_process_error_in_table(): void {
         $record = reset($records);
 
         $this->assertEquals($this->course->id, $record->courseid);
-        if (version_compare(PHP_VERSION, '8.0', '<')) {
-            $this->assertStringContainsString("Trying to get property 'id' of non-object", $record->errormessage);
-        } else {
-            $this->assertStringContainsString("Attempt to read property \"id\" on bool", $record->errormessage);
-        }
+        // We may not know the exact error message.
+        // For example, if there are other plugins that implement the pre_course_delete hook,
+        // We will get different error messages, when those plugin trying to access course modules.
+        $this->assertNotEmpty($record->errormessage);
         $this->assertEquals($process->id, $record->id);
     }