Fix formatting of bigfile json files

lua/plugins/conform.lua

@@ -8,17 +8,26 @@ local oxfmt_owned = {
   "vue",
 }
 
+local function oxfmt_with_prettier_fallback()
+  return { "oxfmt", "prettier", stop_after_first = true }
+end
+
 return {
   "stevearc/conform.nvim",
   opts = function(_, opts)
     opts.formatters_by_ft = opts.formatters_by_ft or {}
     for _, ft in ipairs(oxfmt_owned) do
-      local formatters = opts.formatters_by_ft[ft]
-      if formatters then
-        opts.formatters_by_ft[ft] = vim.tbl_filter(function(formatter)
-          return formatter ~= "prettier"
-        end, formatters)
+      opts.formatters_by_ft[ft] = oxfmt_with_prettier_fallback()
+    end
+
+    -- snacks.bigfile uses "bigfile" as the buffer filetype and preserves the
+    -- original filetype in 'syntax'. Let Conform format supported big files
+    -- without re-enabling Treesitter, LSP, and the other disabled features.
+    opts.formatters_by_ft.bigfile = function(bufnr)
+      if vim.tbl_contains(oxfmt_owned, vim.bo[bufnr].syntax) then
+        return oxfmt_with_prettier_fallback()
       end
+      return {}
     end
   end,
 }