close task before returning from prompt!

Author: IanButterworth

stdlib/REPL/src/LineEdit.jl

@@ -2827,6 +2827,7 @@ function prompt!(term::TextTerminal, prompt::ModalInterface, s::MIState = init_s
     Base.reseteof(term)
     raw!(term, true)
     enable_bracketed_paste(term)
+    t = nothing
     try
         activate(prompt, s, term, term)
         old_state = mode(s)
@@ -2876,6 +2877,10 @@ function prompt!(term::TextTerminal, prompt::ModalInterface, s::MIState = init_s
             end
         end
     finally
+        if t !== nothing
+            put!(s.async_channel, Returns(:done))
+            wait(t)
+        end
         raw!(term, false) && disable_bracketed_paste(term)
     end
     # unreachable