fixup: fix init window and fetch limit calculation

Author: alltilla

modules/grpc/common/grpc-source.cpp

@@ -47,10 +47,13 @@ SourceDriver::init()
 
   ::grpc::EnableDefaultHealthCheckService(true);
 
-  this->super->super.worker_options.super.init_window_size /= super->super.num_workers;
-
   if (fetch_limit == -1)
-    fetch_limit = this->super->super.worker_options.super.init_window_size;
+    {
+      if (super->super.worker_options.super.init_window_size != -1)
+        fetch_limit = super->super.worker_options.super.init_window_size / super->super.num_workers;
+      else
+        fetch_limit = 100;
+    }
 
   return log_threaded_source_driver_init_method(&this->super->super.super.super.super);
 }