Hi,
I'm not able to reproduce the problem on my end.
Note that if you have a plugin crashing the whole backend, you can rename the folder of the plugin via FTP so that Joomla doesn't find it.
For example, this plugin is in plugins/system/custom_price_word_count/ so you can rename it to plugins/system/custom_price_word_count_tmp/ for example to remove the plugin and thus the error.
Could you do this ?
- activate the "debug" setting of the Joomla configuration
- install and activate again the plugin
- get the full error message
- rename the folder of the plugin via FTP and disable the debug setting
That way we could get the full error message to better understand what's going on in order to tell you what to do.