update goto cache when a module cache exists but there is no correspo…

…nding entry for a given file path

this can happen for `Main` module, or when an user manually changes a 
module

src/goto.jl

@@ -155,7 +155,16 @@ gen_new_cache() = PathItemsMap()
 function toplevelgotoitems(word, mod, path, text)
   key = string(mod)
   pathitemsmap = if haskey(SYMBOLSCACHE, key)
-    SYMBOLSCACHE[key]
+    if haskey(SYMBOLSCACHE[key], path)
+      SYMBOLSCACHE[key]
+    else
+      orig = SYMBOLSCACHE[key]
+      maybe = collecttoplevelitems(mod, path, text)
+      if maybe !== nothing
+        merge!(orig, maybe)
+      end
+      orig
+    end
   else
     maybe = collecttoplevelitems(mod, path, text)
     if maybe === nothing