fix: unsigned underflow on empty array

src/arr.c

@@ -13,6 +13,10 @@ unsigned int arr_uint_index_of(UintArray array, unsigned int value) {
 }
 
 unsigned int arr_uint_remap_index(UintArray offsets, unsigned int *index) {
+  if (offsets.length == 0) {
+    return 0;
+  }
+
   for (unsigned int i = offsets.length - 1; i > 0; i--) {
     if (*index >= offsets.values[i]) {
       *index -= offsets.values[i];