LuaSyntaxChecker.lua

-- Any time a lua file is saved, this compiles it and checks for
-- syntax errors. Errors are added as inline annotations

editor1.AnnotationVisible = ANNOTATION_BOXED
editor2.AnnotationVisible = ANNOTATION_BOXED

npp.AddEventHandler("OnSave", function(filename, bufferid)
 if npp:GetExtPart() ~= ".lua" then return false end

 editor:AnnotationClearAll()

 -- Try to compile the lua code
 local _, err = load(editor:GetText(0, editor.Length), npp:GetFileName(), "t")

 -- See if it worked
 if err == nil then return false end

 print(err)
 local line = tonumber(err:match(":(%d+):")) - 1
 editor.AnnotationText[line] = err
 editor.AnnotationStyle[line] = STYLE_BRACELIGHT
 editor:GotoLine(line)
 editor:VerticalCentreCaret()
 return false
end)