Show a helpful message when no Port is selected

Author: PaulStoffregen

app/src/processing/app/SketchController.java

@@ -709,6 +709,10 @@ private boolean upload(String suggestedClassName, boolean usingProgrammer) throw
 
     UploaderUtils uploaderInstance = new UploaderUtils();
     Uploader uploader = uploaderInstance.getUploaderByPreferences(false);
+    if (uploader == null) {
+      editor.statusError(tr("Please select a Port before Upload"));
+      return false;
+    }
 
     EditorConsole.setCurrentEditorConsole(editor.console);
 

arduino-core/src/cc/arduino/UploaderUtils.java

@@ -50,7 +50,16 @@ public Uploader getUploaderByPreferences(boolean noUploadPort) {
 
     BoardPort boardPort = null;
     if (!noUploadPort) {
-      boardPort = BaseNoGui.getDiscoveryManager().find(PreferencesData.get("serial.port"));
+      String port = PreferencesData.get("serial.port");
+      if (port == null || port.isEmpty()) {
+        return null;
+      }
+      boardPort = BaseNoGui.getDiscoveryManager().find(port);
+      //if (boardPort == null) {
+        // Is there ever a reason to attempt upload when
+        // the Port is not found by DiscoveryManager?
+        //return null;
+      //}
     }
 
     return new UploaderFactory().newUploader(target.getBoards().get(board), boardPort, noUploadPort);