Fix single line begin-end blocks

TODO: Should probably require leading and trailing newlines in such
blocks?

src/runestone.jl

@@ -1299,9 +1299,10 @@ function indent_begin(ctx::Context, node::Node, block_kind = K"begin")
         any_kid_changed = true
     end
     # Second node is the newline
-    ln_idx = 2
-    ln_node = kids[ln_idx]
-    @assert is_leaf(ln_node) && kind(ln_node) === K"NewlineWs"
+    # TODO: Require newline?
+    # ln_idx = 2
+    # ln_node = kids[ln_idx]
+    # @assert is_leaf(ln_node) && kind(ln_node) === K"NewlineWs"
     # After the NewlineWs node we skip over all kids until the end
     end_idx = findlast(x -> kind(x) === K"end", kids)
     @assert end_idx == lastindex(kids) # ??

test/runtests.jl

@@ -567,8 +567,11 @@ end
             @test format_string("$(t)[a b\n$(sp)c d]") == "$(t)[\n    a b\n    c d\n]"
             @test format_string("$(t)[\n$(sp)a b\n$(sp)c d\n$(sp)]") == "$(t)[\n    a b\n    c d\n]"
         end
+        # Single line begin-end
+        @test format_string("begin x\n$(sp)end") == "begin x\nend"
+        @test format_string("begin x end") == "begin x end"
+        @test format_string("begin\n    x end") == "begin\n    x end"
     end
-
 end
 
 @testset "continuation/soft indentation" begin