joining a thread not joinable is no more returning EINVAL
Its behaviour is undefined
--- a/tests/thread.test	2023-03-16 21:31:05.333423098 +0100
+++ b/tests/thread.test	2023-03-16 21:31:25.837324400 +0100
@@ -100,15 +100,6 @@
     set c
 } {0}
 
-test thread-4.5 {thread::create - join detached thread} {
-    ThreadReap
-    set tid [thread::create]
-    thread::send -async $tid {after 1000 ; thread::release}
-    catch {set res [thread::join $tid]} msg
-    ThreadReap
-    lrange $msg 0 2
-} {cannot join thread}
-
 test thread-5.0 {thread::release} {
     ThreadReap
     set tid [thread::create {thread::release}]