wifi(implementation): Check if wifi_chip is null in debug()

|chip_| could be null if wifi is not turned on.

Bug: 72470346
Test: Ensure that the device does not crash when bugreport is collected
with wifi off.

Change-Id: Iface5ecf0511ad88996ebad85ba3c037c3a8c5ee
diff --git a/wifi/1.2/default/wifi.cpp b/wifi/1.2/default/wifi.cpp
index d6106b4..79f921f 100644
--- a/wifi/1.2/default/wifi.cpp
+++ b/wifi/1.2/default/wifi.cpp
@@ -80,6 +80,9 @@
 Return<void> Wifi::debug(const hidl_handle& handle,
                          const hidl_vec<hidl_string>&) {
     LOG(INFO) << "-----------Debug is called----------------";
+    if (!chip_.get()) {
+        return Void();
+    }
     return chip_->debug(handle, {});
 }