Merge pull request #25598 from asmorkalov:as/tables_range_check_core

Check range for type-dependant function tables #25598

Address https://github.com/opencv/opencv/issues/24703

### 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
- [ ] 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/core/src/channels.cpp

@@ -79,7 +79,7 @@ typedef void (*MixChannelsFunc)( const void** src, const int* sdelta,
 
 static MixChannelsFunc getMixchFunc(int depth)
 {
-    static MixChannelsFunc mixchTab[] =
+    static MixChannelsFunc mixchTab[CV_DEPTH_MAX] =
     {
         mixChannels8u, mixChannels8u, mixChannels16u,
         mixChannels16u, mixChannels32s, mixChannels32s,
@@ -146,6 +146,7 @@ void cv::mixChannels( const Mat* src, size_t nsrcs, Mat* dst, size_t ndsts, cons
     NAryMatIterator it(arrays, ptrs, (int)(nsrcs + ndsts));
     int total = (int)it.size, blocksize = std::min(total, (int)((BLOCK_SIZE + esz1-1)/esz1));
     MixChannelsFunc func = getMixchFunc(depth);
+    CV_Assert(func);
 
     for( i = 0; i < it.nplanes; i++, ++it )
     {