fix handling of explicitly null options

README.md

@@ -763,6 +763,7 @@ This library makes no attempt to interpret the Language Encoding Flag.
      Added fields to `Class: Entry`: `fileNameRaw`, `extraFieldRaw`, `fileCommentRaw`.
    * Added `examples/compareCentralAndLocalHeaders.js` that demonstrate many of these low level APIs.
    * Noted dropped support of node versions before 12 in the `"engines"` field of `package.json`.
+   * Fixed a crash when calling `openReadStream()` with an explicitly `null` options parameter (as opposed to omitted).
  * 3.0.0
    * BREAKING CHANGE: implementations of [RandomAccessReader](#class-randomaccessreader) that implement a `destroy` method must instead implement `_destroy` in accordance with the node standard https://nodejs.org/api/stream.html#writable_destroyerr-callback (note the error and callback parameters). If you continue to override `destory` instead, some error handling may be subtly broken. Additionally, this is required for async iterators to work correctly in some versions of node. [issue #110](https://github.com/thejoshwolfe/yauzl/issues/110)
    * BREAKING CHANGE: Drop support for node versions older than 12.

index.js

@@ -402,6 +402,9 @@ ZipFile.prototype.openReadStream = function(entry, options, callback) {
   var relativeEnd = entry.compressedSize;
   if (callback == null) {
     callback = options;
+    options = null;
+  }
+  if (options == null) {
     options = {};
   } else {
     // validate options that the caller has no excuse to get wrong
@@ -519,8 +522,9 @@ ZipFile.prototype.readLocalFileHeader = function(entry, options, callback) {
   var self = this;
   if (callback == null) {
     callback = options;
-    options = {};
+    options = null;
   }
+  if (options == null) options = {};
 
   self.reader.ref();
   var buffer = newBuffer(30);
@@ -754,6 +758,7 @@ RandomAccessReader.prototype.unref = function() {
   }
 };
 RandomAccessReader.prototype.createReadStream = function(options) {
+  if (options == null) options = {};
   var start = options.start;
   var end = options.end;
   if (start === end) {