fix(errors): Fix error messages

Author: Walker

lib/reader.js

@@ -1,4 +1,4 @@
-const { Readable, PassThrough, Transform } = require('stream');
+const { Readable, PassThrough, Transform, Stream } = require('stream');
 const { stringify, parse } = require('JSONStream');
 const mergeStream = require('merge-stream');
 const { dedupe, sort, setOrder } = require('./util');
@@ -9,7 +9,7 @@ module.exports = class Reader extends Readable {
         super();
 
         assert(
-            streams,
+            streams instanceof Stream || Array.isArray(streams),
             `Expected first argument to new Reader() to be a stream or array of streams. 
             Instead got ${typeof stream}`
         );
@@ -18,6 +18,11 @@ module.exports = class Reader extends Readable {
             streams = [streams];
         }
 
+        assert(
+            streams.every(stream => stream instanceof Stream),
+            `Expected any/all arguments given to Reader constructor to be subclasses of Stream.`
+        );
+
         assert(
             streams.length,
             `Expected at least one stream to be provided to new Reader(). Got none.`

test/__snapshots__/reader.test.js.snap

@@ -7,6 +7,9 @@ exports[`new Reader(): throws on no input 1`] = `
 
 exports[`new Reader([]): throws on empty array 1`] = `"Expected at least one stream to be provided to new Reader(). Got none."`;
 
-exports[`new Reader([1,2,3]): throws on array containing non stream items 1`] = `"readStream.on is not a function"`;
+exports[`new Reader([1,2,3]): throws on array containing non stream items 1`] = `"Expected any/all arguments given to Reader constructor to be subclasses of Stream."`;
 
-exports[`new Reader(123): throws on non stream or array input 1`] = `"readStream.on is not a function"`;
+exports[`new Reader(123): throws on non stream or array input 1`] = `
+"Expected first argument to new Reader() to be a stream or array of streams. 
+            Instead got undefined"
+`;