Bump questionable and test for tree init failure (#630)

tests/codex/merkletree/testmerkletree.nim

@@ -50,6 +50,12 @@ checksuite "merkletree":
     zeroHash = MultiHash.init($sha256, zero).tryGet()
     oneHash = MultiHash.init($sha256, one).tryGet()
 
+  test "cannot init tree without any leafs":
+    let treeOrErr = MerkleTree.init(newSeq[MultiHash]())
+
+    check:
+      treeOrErr.isErr
+
   test "tree with one leaf has expected structure":
     builder.addDataBlock(data[0]).tryGet()
 

vendor/questionable

@@ -1 +1 @@
-Subproject commit 2dd6b6b220f9f14a1231f6cafdf24f012bcc8414
+Subproject commit 1f0afff48bf80ab1149a0957f9743f345bc14b71