Fix the crash of CallObjectMethod. (#959)

Co-authored-by: kevingpqi <kevingpqi@tencent.com>
(cherry picked from commit 5cc6f6f)

tgfx/src/platform/android/NativeCodec.cpp

@@ -230,6 +230,9 @@ static jobject ConvertHardwareBitmap(JNIEnv* env, jobject bitmap) {
  // The AndroidBitmapInfo does not contain the ANDROID_BITMAP_FLAGS_IS_HARDWARE flag in the old
  // versions of Android NDK, even when the Java Bitmap has the hardware config. So we check it here
  // by the Java-side methods.
+ if (bitmap == nullptr) {
+ return nullptr;
+ }
  if (BitmapConfig_HARDWARE == nullptr) {
  return bitmap;
  }