fix(hint): attempt to index a nil value

Fixes: #2788

Author: tmillr

script/core/hint.lua

@@ -287,6 +287,7 @@ local function semicolonHint(uri, results, start, finish)
     ---@async
     guide.eachSourceTypes(state.ast, blockTypes, function (src)
         await.delay()
+        if #src < 1 then return end
         for i = 1, #src - 1 do
             local current = src[i]
             local next    = src[i+1]