libc: Fix some environment-related bugs

libc/src/env.cpp

@@ -54,10 +54,10 @@ static Result<void> _try_move_env()
 
     if (!env)
     {
+        TRY(g_dynamic_env.try_append(nullptr));
         guard.deactivate();
         env_is_dynamic = true;
         environ = g_dynamic_env.data();
-        check(!environ);
         return {};
     }
 
@@ -109,10 +109,12 @@ extern "C"
             {
                 if (element) free(element);
             }
+
+            g_dynamic_env.clear();
         }
 
-        env_is_dynamic = false;
         environ = nullptr;
+        env_is_dynamic = false;
 
         return 0;
     }