Remove leading whitespace in the beginning of a file

This is needed to "bootstrap" the indent process since there isn't a
leading newline to indent to level 0 when there is leading whitespace.

src/runestone.jl

@@ -1357,12 +1357,14 @@ function no_leading_and_single_trailing_newline(ctx::Context, node::Node)
     @assert !is_leaf(node)
     @assert position(ctx.fmt_io) == 0
     changed = false
-    while (l = first_leaf(node); l !== nothing && kind(l) === K"NewlineWs" && length(verified_kids(node)) > 1)
+    # Remove leading newlines and whitespace
+    while (l = first_leaf(node); l !== nothing && kind(l) in KSet"NewlineWs Whitespace" && length(verified_kids(node)) > 1)
         changed = true
         replace_bytes!(ctx, "", span(l))
         node = replace_first_leaf(node, nullnode)
     end
     accept_node!(ctx, node)
+    # Remove trailing newlines
     l = last_leaf(node)
     if l === nothing || kind(l) !== K"NewlineWs"
         kids′ = copy(verified_kids(node))

test/runtests.jl

@@ -775,6 +775,7 @@ end
         @test format_string("$(nl)f()$(nl)"; filemode = true) == "f()\n"
         @test format_string("$(nl)"; filemode = true) == "\n"
     end
+    @test format_string(" x\n"; filemode = true) == "x\n"
 end
 
 @testset "https://youtu.be/SsoOG6ZeyUI?si=xpKpnczuqsOThtFP" begin