Declare variables before use (#6806)

While working on #6805, I noticed that many variables were being used
before they were declared. Technically this worked fine in practice
because we were using the `transform-es2015-block-scoping` Babel plugin,
which transforms `let` and `const` to `var`, which is hoisted. However,
after removing that Babel transformation, many things broke.

All instances of variables or classes being used before declared have
been fixed.

The `no-use-before-define` eslint rule has been added to catch these
cases going forward. The rule is disabled for function declarations for
the moment, because those are always hoisted. We could disable that too
if we want to, but it's purely stylistic and would require a lot more
changes.

1 files changed, 6 insertions, 7 deletions

diff --git a/app/scripts/lib/createStreamSink.js b/app/scripts/lib/createStreamSink.js
index b93dbc089..eb9d0bd1a 100644
--- a/app/scripts/lib/createStreamSink.js
+++ b/app/scripts/lib/createStreamSink.js
@@ -1,13 +1,6 @@
 const WritableStream = require('readable-stream').Writable
 const promiseToCallback = require('promise-to-callback')
 
-module.exports = createStreamSink
-
-
-function createStreamSink (asyncWriteFn, _opts) {
-  return new AsyncWritableStream(asyncWriteFn, _opts)
-}
-
 class AsyncWritableStream extends WritableStream {
 
   constructor (asyncWriteFn, _opts) {
@@ -22,3 +15,9 @@ class AsyncWritableStream extends WritableStream {
   }
 
 }
+
+function createStreamSink (asyncWriteFn, _opts) {
+  return new AsyncWritableStream(asyncWriteFn, _opts)
+}
+
+module.exports = createStreamSink