Fix edgecases in spaces in operator call chains

This patch fixes a bug where, in an operator call chain, whitespace was
borrows from the next child, but the call chain continued after.

src/runestone.jl

@@ -203,6 +203,8 @@ function spaces_around_x(ctx::Context, node::JuliaSyntax.GreenNode, is_x::F) whe
                 # Whitespace found at the beginning of next child.
                 child_ws = first_leaf(child)
                 looking_for_whitespace = JuliaSyntax.kind(last_leaf(child)) !== K"Whitespace"
+                @assert !is_x(child)::Bool
+                looking_for_x = true
                 if JuliaSyntax.span(child_ws) == 1
                     # Accept the node
                     accept_node!(ctx, child)
@@ -216,6 +218,7 @@ function spaces_around_x(ctx::Context, node::JuliaSyntax.GreenNode, is_x::F) whe
                     remaining_bytes_inclusive =
                         @view original_bytes[(span_sum + 1 + bytes_to_skip - JuliaSyntax.span(child)):end]
                     write_and_reset(ctx, remaining_bytes_inclusive)
+                    accept_node!(ctx, child′)
                     any_changes = true
                     if children′ === children
                         children′ = children[1:i - 1]

test/runtests.jl

@@ -143,6 +143,9 @@ end
         # JuliaSyntax.jl decides to place the K"Whitespace" node.
         @test format_string("$(sp)a$(sp)+$(sp)b$(sp)*$(sp)c$(sp)/$(sp)d$(sp)") ==
             "$(sp)a + b * c / d$(sp)"
+        # Edgecase when using whitespace from the next leaf but the call chain continues
+        # after with more children.
+        @test format_string("$(sp)z$(sp)+$(sp)2x$(sp)+$(sp)z$(sp)") == "$(sp)z + 2x + z$(sp)"
     end
 end