fix: Add missing validation for insert mode

Author: andrewferrier

lua/debugprint/options.lua

@@ -68,6 +68,7 @@ local validate_global_opts = function(o)
     })
 
     local normal = o.keymaps.normal
+    local insert = o.keymaps.insert
     local visual = o.keymaps.visual
 
     if normal ~= nil then
@@ -94,6 +95,13 @@ local validate_global_opts = function(o)
         })
     end
 
+    if insert ~= nil then
+        vim.validate({
+            variable_below = { insert.plain, STRING_NIL },
+            variable_above = { insert.variable, STRING_NIL },
+        })
+    end
+
     if visual ~= nil then
         vim.validate({
             variable_below = { visual.variable_below, STRING_NIL },