Fix serial upload not working with all boards

Author: silvanocerza

arduino-ide-extension/src/browser/contributions/upload-sketch.ts

@@ -230,8 +230,9 @@ export class UploadSketch extends SketchContribution {
       const optimizeForDebug = this.editorMode.compileForDebug;
       const { selectedPort } = boardsConfig;
       const port = selectedPort;
-      const userFields = this.cachedUserFields.get(this.selectedFqbnAddress());
-      if (!userFields) {
+      const userFields =
+        this.cachedUserFields.get(this.selectedFqbnAddress()) ?? [];
+      if (userFields.length === 0 && this.boardRequiresUserFields) {
         this.messageService.error(
           nls.localize(
             'arduino/sketch/userFieldsNotFoundError',