Merge pull request #27169 from Kumataro:fix27168

Imgcodec: gif: remove unnecessary warning #27169

Close https://github.com/opencv/opencv/issues/27168

### Pull Request Readiness Checklist

See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request

- [x] I agree to contribute to the project under Apache 2 License.
- [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
- [x] The PR is proposed to the proper branch
- [x] There is a reference to the original bug report and related work
- [x] There is accuracy test, performance test and test data in opencv_extra repository, if applicable
      Patch to opencv_extra has the same branch name.
- [ ] The feature is well documented and sample code can be built with the project CMake

modules/imgcodecs/src/grfmt_gif.cpp

@@ -392,8 +392,7 @@ bool GifDecoder::lzwDecode() {
             if (code < colorTableSize) {
                 imgCodeStream[idx++] = (uchar)code;
             } else {
-                CV_LOG_WARNING(NULL, "Too long LZW length in GIF.");
-                CV_Assert(idx + lzwExtraTable[code].length <= width * height);
+                CV_Check(idx, idx + lzwExtraTable[code].length <= width * height, "Too long LZW length in GIF.");
                 for (int i = 0; i < lzwExtraTable[code].length - 1; i++) {
                     imgCodeStream[idx++] = lzwExtraTable[code].prefix[i];
                 }