writing library code is hard.

there are sooo many details that go into writing good libraries:

designing intuitive and powerful apis
deciding good api option defaults, disallowing or warning for illegal operations

knowing when to throw, knowing when to warn/log
handling edge cases
having good code coverage with tests that doesn't suck shit, while ensuring thry don't take a hundred years to run

making the code easy to read, to maintain, robust
and also not vulnerable, which is probably the most overlooked quality.

"too many classes, too little classes"

the functions do too much it's hard to follow them
or the functions are so well abstracted, that every function has 1 line of code, resulting in code that is even harder to understand or debug (have fun drowning in those immense stack traces)

don't forget to be disciplined about the documentation.

most of these things are
deeply affected by the ecosystem, the tools of the language you're writing this in:

like 5 years ago I hated coding in nodejs, because I didn't know about linters, and now we have tools like eslint or babel, so it's more passable now

but now dealing with webpack/babel configs and plugins can literally obliterate your asshole.

some languages don't even have a stable line by line debugger (hard pass for me)

then there's also the several phases of the project:

you first conceive the idea, the api, and try to implement it, write some md's of usage examples.

as you do that, you iterate on the api, you notice that it could better, so you redesign it. once, twice, thrice.

so at that point you're spending days, weeks on this side project, and your boss is like "what the fuck are you doing right now?"

then, you reach fuckinnnnng 0.1.0, with a "frozen" api, put it on github with a shitton of badges like the badge whore you are.

then you drop it on forums, and slack communities and irc, and what do you get?

half of the community wants to ban you for doing self promotion

the other half thinks either
a) your library api is shitty
b) has no real need for it
c) "why reinvent the wheel bruh"

that's one scenario,

the other scenario is the project starts to get traction.

people start to star it and shit.
but now you have one peoblem you didn't have before: humans.

all sorts of shit:

people treating you like shit as if they were premium users.

people posting majestically written issues with titles like "people help, me no work, here" with bodies like "HAAAAAAAAAALP".

and if you have the blessing to work in the current js ecosystem, issues like "this doesn't work with esm, unpkg, cdnjs, babel, webpack, parcel, buble, A BROWSER".
with some occasional lunatic complaining about IE 4 having a very weird, obscure bug.

not the best prospect either.