non-working checkpoint

lua/modules/diagnostics.lua

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+-- Diagnostics
+local special_sources = {
+  lua_ls = 'lua',
+}
+vim.diagnostic.config({
+  underline = true,
+  severity_sort = true,
+  virtual_text = {
+    format = function(diagnostic)
+      local src = diagnostic.source and (special_sources[diagnostic.source] or diagnostic.source)
+      if src then
+        return string.format('%s: %s', src, diagnostic.message)
+      end
+      return diagnostic.message
+    end,
+  },
+  float = {
+    border = 'rounded',
+    header = '',
+    format = function(diagnostic)
+      local src = diagnostic.source and (special_sources[diagnostic.source] or diagnostic.source)
+      if src then
+        return string.format('%s: %s', src, diagnostic.message)
+      end
+      return diagnostic.message
+    end,
+  },
+})
+
+-- Override the virtual text diagnostic handler so that the most severe diagnostic is shown first.
+local show_handler = vim.diagnostic.handlers.virtual_text.show
+assert(show_handler)
+local hide_handler = vim.diagnostic.handlers.virtual_text.hide
+vim.diagnostic.handlers.virtual_text = {
+  show = function(ns, bufnr, diagnostics, opts)
+    table.sort(diagnostics, function(diag1, diag2)
+      return diag1.severity > diag2.severity
+    end)
+    return show_handler(ns, bufnr, diagnostics, opts)
+  end,
+  hide = hide_handler,
+}