@pichalite Hmmm. You might be right. But I would have sworn on a sacred text that I had done that!
OK, but I did it now. And it gets further after I do the node app --setup
And now I'm getting the error message below. Should I start over with a clean install? I haven't messed things up beyond saving, have I?! 
>> community$ node app --setup
22/3 02:08:59 [13955] - info: NodeBB v1.4.5 Copyright (C) 2013-2017 NodeBB Inc.
22/3 02:08:59 [13955] - info: This program comes with ABSOLUTELY NO WARRANTY.
22/3 02:08:59 [13955] - info: This is free software, and you are welcome to redistribute it under certain conditions.
22/3 02:08:59 [13955] - info:
22/3 02:08:59 [13955] - info: NodeBB Setup Triggered via Command Line
Welcome to NodeBB!
This looks like a new installation, so you'll have to answer a few questions about your environment before we can proceed.
Press enter to accept the default setting (shown in brackets).
module.js:328
throw err;
^
Error: Cannot find module 'express-session'
at Function.Module._resolveFilename (module.js:326:15)
at Function.Module._load (module.js:277:25)
at Module.require (module.js:354:17)
at require (internal/module.js:12:17)
at /var/www/nodebb/community/src/database/redis.js:7:16
at Object.<anonymous> (/var/www/nodebb/community/src/database/redis.js:169:2)
at Module._compile (module.js:410:26)
at Object.Module._extensions..js (module.js:417:10)
at Module.load (module.js:344:32)
at Function.Module._load (module.js:301:12)