fix: get device port error on linux

QtScrcpy/dialog.cpp

@@ -182,14 +182,17 @@ void Dialog::on_wirelessConnectBtn_clicked()
         return;
     }
     QString addr = ui->deviceIpEdt->text().trimmed();
-    if (!ui->devicePortEdt->placeholderText().isEmpty()) {
-        addr += ":";
-        addr += ui->devicePortEdt->placeholderText().trimmed();
-    }
     if (!ui->devicePortEdt->text().isEmpty()) {
         addr += ":";
         addr += ui->devicePortEdt->text().trimmed();
+    } else if (!ui->devicePortEdt->placeholderText().isEmpty()) {
+        addr += ":";
+        addr += ui->devicePortEdt->placeholderText().trimmed();
+    } else {
+        outLog("error: device port is null", false);
+        return;
     }
+
     outLog("wireless connect...", false);
     QStringList adbArgs;
     adbArgs << "connect";