Update code to remove "return new Promise()" in subroutines

[Misterblue]

I used the previous convention of returning a "new Promise()" in subroutines that return a Promise. But Javascript will wrap things in Promises if one doesn't do that. So, the popular convention these days is to just return the value and throw the error and let Javascript do the Promise magic.

Related is using await/try/catch instead of .then/.catch. This sometimes creates less verbose code.