Added assertions on inline size to btree inline code

This was missed when moving to use lfsr_data_t more. This is interesting
conflict between implicit truncation in lfsr_data_read and strict
assertions that inlined btree don't lose data.

Found in the btree tests when, you guessed it, inlined btrees lost data.

An alternative route would be to make btrees uninline when faced with an
entry too big to inlined. This may be valuable future work, but probably
depends on the file implementation to know if such a feature is useful.

lfs.c

@@ -3543,6 +3543,7 @@ static lfs_ssize_t lfsr_btree_todisk(lfs_t *lfs, const lfsr_rbyd_t *btree,
 static int lfsr_data_readbtreeinlined(lfs_t *lfs, lfsr_data_t *data,
         lfsr_tag_t tag, lfs_size_t weight,
         lfsr_btree_t *btree) {
+    LFS_ASSERT(lfsr_data_size(data) <= LFSR_BTREE_INLINESIZE);
     // mark as inlined
     btree->u.i.weight = lfsr_btree_setinlined(weight);
     btree->u.i.tag = tag;
@@ -3794,6 +3795,8 @@ static int lfsr_btree_commit(lfs_t *lfs, lfsr_btree_t *btree,
                 // update our inlined tag, make sure to strip wide/grow bits
                 if (lfsr_tag_suptype(lfsr_tag_key(attrs[i].tag))
                         == LFSR_TAG_STRUCT) {
+                    LFS_ASSERT(lfsr_data_size(&attrs[i].data)
+                            <= LFSR_BTREE_INLINESIZE);
                     btree->u.i.tag = lfsr_tag_key(attrs[i].tag);
 
                     lfsr_data_t data_ = attrs[i].data;