tpm generates unknown variable: TMUX_PLUGIN_MANAGER_PATH

[EdmundsEcho]

In trying to identify what seems like a "long" delay (whatever that means, but I guess I mean "more noticeable"), I found the following error in the tmux logs:

1688747298.543603 cmdq_error: unknown variable: TMUX_PLUGIN_MANAGER_PATH

This might be because I'm not overriding the default value (i.e., my configs do not set that env value). However, in tpm/scripts/variables.sh does set the DEFAULT_TMP_ENV_VAR_NAME to TMUX_PLUGIN_MANAGER_PATH.

There is a chance this is in fact a bit of a bug: trying to read the value before the default value was used to assign the value. To the degree it's not an error, it may be useful to prevent the error log output.