Display yaml errors outside tmux if session name is not found

bliss/shell/main.py

@@ -165,13 +165,18 @@ def main():
             sys.exit(0)
 
     # check beacon connection
-    static.get_config()
+    config = static.get_config()
 
     # Start a specific session
     if arguments["--session"]:
         session_name = arguments["--session"]
         if session_name not in get_sessions_list():
-            print(("'%s' does not seem to be a valid session, exiting." % session_name))
+            print(f"\n'{session_name}' does not seem to be a valid session, ", end="")
+            if config.invalid_yaml_files:
+                print("it may relate to the following yaml error(s):")
+                config.parsing_report()
+            else:
+                print("exiting.")
             print_sessions_list(get_sessions_list())
             sys.exit(0)
     else: