Fix let block without variables

src/runestone.jl

@@ -1314,7 +1314,9 @@ function indent_let(ctx::Context, node::Node)
     vars_idx = 2
     vars_node = kids[vars_idx]
     @assert !is_leaf(vars_node) && kind(vars_node) === K"block"
+    if span(vars_node) > 0 && length(verified_kids(vars_node)) > 0
         @assert kind(last_leaf(vars_node)) !== "NewlineWs"
+    end
     # Third node is the NewlineWs before the block
     ln_idx = 3
     ln_node = kids[ln_idx]

test/runtests.jl

@@ -453,6 +453,8 @@ end
         # let-end
         @test format_string("let a = 1\n$(sp)x\n$(sp)end") ==
             "let a = 1\n    x\nend"
+        @test format_string("let\n$(sp)x\n$(sp)end") ==
+            "let\n    x\nend"
         # begin-end
         @test format_string("begin\n$(sp)x\n$(sp)end") ==
             "begin\n    x\nend"