Meaningful Errors On Invalid Input?

[jamescarr]

Ran across this issue today with some user code on our site:

~ ❯ node
> var async = require('async')
undefined
> async.map(process.nosir, function() {}, function() {});
TypeError: Cannot read property 'map' of undefined
    at _map (/home/vagrant/node_modules/async/lib/async.js:54:16)
    at _asyncMap (/home/vagrant/node_modules/async/lib/async.js:237:15)
    at Object.map (/home/vagrant/node_modules/async/lib/async.js:219:23)
    at repl:1:7
    at REPLServer.self.eval (repl.js:110:21)
    at repl.js:249:20
    at REPLServer.self.eval (repl.js:122:7)
    at Interface.<anonymous> (repl.js:239:12)
    at Interface.emit (events.js:95:17)
    at Interface._onLine (readline.js:202:10)

Is it possible to do some kind of assertion or something at the beginning of the method to ensure that invalid data is not passed in?

[beaugunderson]

(I'm mostly just helping out with docs, but to clarify:) Would you expect it to still throw an error in the same place but with a more helpful message?

[jamescarr]

Right. Would expect it to throw an error, just something more meaningful. Something like AssertionError: async.map called with non-array value.

On Fri, Nov 21, 2014 at 5:42 PM, Beau Gunderson [email protected]
wrote:

(I'm mostly just helping out with docs, but to clarify:) Would you expect
it to still throw an error in the same place but with a more helpful
message?

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#667 (comment).

[aearly]

Another option would be to treat a null or undefined array as an empty array. Libraries like lodash do this.

[jamescarr]

👍 I'm more of a fan of being graceful about it to be honest!

On Sat, Nov 22, 2014 at 6:27 PM, Alexander Early [email protected]
wrote:

Another option would be to treat a null or undefined array as an empty
array. Libraries like lodash do this.

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#667 (comment).

[beaugunderson]

@jamescarr Just to be clear, are you saying you prefer the lodash approach of treating null/undefined as empty arrays? (And what should happen if you pass in an object?)

[jlg-rayalab]

Still crashing,

fixed adding this in line 120:
if (typeof arr === "undefined") {
return callback();
}