…#40643)

## Proposed changes

### Issue
```
*** is nereids: 1 ***
tablet id: 4
Abort at 1725864966 (unix time) try "date -d @1725864966" if you are using GNU date ***
*** Set a breakpoint in static void __GI_abort() to debug ***
PC: @ 0x7f007fb4090a04
*** SIGSEGV (address not mapped to object 0xa0fa868a41d6) received by PID 404737 (TID 274135 OR 0x7ece29df700) from PID 1755584205; stack trace: ***
#0 __GI_raise
#1 __GI_abort
#2 sig_handler
apache#3 _sigaction
apache#4 JVM_handle_linux_signal
apache#5 _sigaction
apache#6 doris::vectorized::ByteArrayDictDecoder::set_dict(std::unique_ptr<unsigned char[], std::default_delete<unsigned char[]>> &&, int, unsigned long)
at /mnt/disk1/yy/git/enterprise-core/be/src/vec/exec/format/parquet/byte_array_dict_decoder.cpp:41
apache#7 doris::vectorized::ColumnChunkReader::_decode_dict_page() at /mnt/disk1/yy/git/enterprise-core/be/src/vec/exec/format/parquet/vparquet_column_chunk_reader.cpp:258
apache#8 doris::vectorized::ColumnChunkReader::next_page() at /mnt/disk1/yy/git/enterprise-core/be/src/vec/exec/format/parquet/vparquet_column_chunk_reader.cpp:105
apache#9 doris::vectorized::ParquetColumnReader::_read_column_data(doris::vectorized::Block*, bool*) at /mnt/disk1/yy/git/enterprise-core/be/src/vec/exec/format/parquet/vparquet_column_reader.cpp:508
apache#10 doris::vectorized::ScalarColumnReader::_next_value(doris::vectorized::ICollumn*, unsigned long, unsigned long*, bool*) at /mnt/disk1/yy/git/enterprise-core/be/src/vec/exec/format/parquet/vparquet_column_reader.cpp:699
apache#11 doris::vectorized::RowGroupReader::_read_column_data(doris::vectorized::Block*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>> &, std::vector<doris::vectorized::ColumnSelectVector>*, unsigned long, unsigned long*, bool*) at /mnt/disk1/yy/git/enterprise-core/be/src/vec/exec/format/parquet/vparquet_group_reader.cpp:425
apache#12 doris::vectorized::RowGroupReader::get_next_block(doris::vectorized::Block*, bool*) at /mnt/disk1/yy/git/enterprise-core/be/src/vec/exec/format/parquet/vparquet_group_reader.cpp:311
apache#13 doris::vectorized::ParquetReader::get_next(doris::vectorized::Block*, bool*) at /mnt/disk1/yy/git/enterprise-core/be/src/vec/exec/format/parquet/vparquet_reader.cpp:533
apache#14 doris::vectorized::VFileScanner::_get_next_reader_block(doris::RuntimeState*, doris::vectorized::Block*, bool*) at /mnt/disk1/yy/git/enterprise-core/be/src/vec/exec/scan/vfile_scanner.cpp:368
apache#15 doris::vectorized::VFileScanner::_get_block_impl(doris::RuntimeState*, doris::vectorized::Block*, bool*) at /mnt/disk1/yy/git/enterprise-core/be/src/vec/exec/scan/vfile_scanner.cpp:411
apache#16 doris::vectorized::VScanner::get_block(doris::RuntimeState*, doris::vectorized::Block*, bool*) at /mnt/disk1/yy/git/enterprise-core/be/src/vec/exec/scan/vscanner.cpp:431
apache#17 doris::vectorized::VScanner::get_block(doris::RuntimeState*, doris::vectorized::Block*, bool*) at /mnt/disk1/yy/git/enterprise-core/be/src/vec/exec/scan/vscanner.cpp:96
apache#18 doris::vectorized::ScannerScheduler::submit(doris::vectorized::ScannerContext*, std::shared_ptr<doris::vectorized::ScanTask>) at /mnt/disk1/yy/git/enterprise-core/be/src/vec/exec/scan/scanner_context.cpp:96
apache#19 doris::Thread::supervise_thread(void*) at /mnt/disk1/yy/git/enterprise-core/be/src/util/thread.cpp:499
apache#20 start_thread
apache#21 clone in /lib64/libc.so.6
```

### Solution
It is not known why the parquet dictionary page will be null in this
case, causing a crash. This PR adds defensive code to prevent the crash.