fix: use checked conversion for AVX2 table limit

Signed-off-by: Joe Isaacs <joe.isaacs@live.co.uk>

Author: joseph-isaacs

vortex-array/src/arrays/fixed_width/take/small_table/avx2.rs

@@ -25,6 +25,7 @@ use arch::_mm256_testz_si256;
 use vortex_buffer::Buffer;
 use vortex_buffer::BufferAllocatorRef;
 use vortex_buffer::BufferMut;
+use vortex_error::VortexExpect;
 
 use super::super::FixedWidthTakeValue;
 use super::super::HAS_AVX2;
@@ -99,7 +100,9 @@ unsafe fn take_avx2<T: FixedWidthTakeValue>(
     // SAFETY: the table contains 16 initialized one-byte values.
     let table = unsafe { _mm_loadu_si128(table.as_ptr().cast()) };
     let table = _mm256_broadcastsi128_si256(table);
-    let limit = _mm256_set1_epi8((values.len() - 1) as i8);
+    let limit = _mm256_set1_epi8(
+        i8::try_from(values.len() - 1).vortex_expect("table contains at most 16 values"),
+    );
     let mut invalid = _mm256_setzero_si256();
     let mut output = BufferMut::<T>::with_capacity_in(indices.len(), allocator.clone());
     let spare = output.spare_capacity_mut();