Fixed Java exception if mConnection is null

android-project/app/src/main/java/org/libsdl/app/HIDDeviceUSB.java

@@ -154,6 +154,11 @@ class HIDDeviceUSB implements HIDDevice {
 
     @Override
     public int writeReport(byte[] report, boolean feature) {
+        if (mConnection == null) {
+            Log.w(TAG, "writeReport() called with no device connection");
+            return -1;
+        }
+
         if (feature) {
             int res = -1;
             int offset = 0;
@@ -201,6 +206,11 @@ class HIDDeviceUSB implements HIDDevice {
         boolean skipped_report_id = false;
         byte report_number = report[0];
 
+        if (mConnection == null) {
+            Log.w(TAG, "readReport() called with no device connection");
+            return false;
+        }
+
         if (report_number == 0x0) {
             /* Offset the return buffer by 1, so that the report ID
                will remain in byte 0. */