avoid chunk is undefined. (openstf#127)

* avoid “chunk is undefined”

Signed-off-by: renchao <renchao@huya.com>

* fix: avoid chunk maybe undefined

Signed-off-by: renchao <renchao@huya.com>

* avoid chunk is undefined

Signed-off-by: renchao <renchao@huya.com>

Co-authored-by: renchao <renchao@huya.com>

Author: rcpirate

src/adb/parser.ts

@@ -181,10 +181,11 @@ export default class Parser {
     return new Bluebird<void>((resolve, reject /*, onCancel*/) => {
       tryRead = () => {
         if (howMany) {
-          const chunk = this.stream.read(howMany);
           // Try to get the exact amount we need first. If unsuccessful, take
           // whatever is available, which will be less than the needed amount.
-          while (chunk || this.stream.read()) {
+          // avoid chunk is undefined.
+          let chunk;
+          while (chunk = this.stream.read(howMany) || this.stream.read()) {
             howMany -= chunk.length;
             targetStream.write(chunk);
             if (howMany === 0) {