Fix for the 'start' range of BlobDataItem when reading its stream (#85)

Set default value for 'start' option

from.js

@@ -23,7 +23,7 @@ class BlobDataItem {
 	constructor(options) {
 		this.size = options.size;
 		this.path = options.path;
-		this.start = options.start;
+		this.start = options.start || 0;
 		this.mtime = options.mtime;
 	}
 

test.js

@@ -163,6 +163,15 @@ test('Reading after modified should fail', async t => {
 	t.is(error.name, 'NotReadableError');
 });
 
+test('Reading from the stream created by blobFrom', async t => {
+	const blob = blobFrom('./LICENSE');
+	const expected = await fs.promises.readFile('./LICENSE', 'utf-8');
+
+	const actual = await getStream(blob.stream());
+
+	t.is(actual, expected);
+});
+
 test('Blob-ish class is an instance of Blob', t => {
 	class File {
 		stream() {}