fix #375 - location are null

Author: ichiriac

src/parser/utils.js

@@ -112,10 +112,12 @@ module.exports = {
   read_byref: function(cb) {
     let byref = this.node("byref");
     this.next();
-    byref = byref();
+    byref = byref(null);
     const result = cb();
-    this.ast.swapLocations(result, byref, result, this);
-    result.byref = true;
+    if (result) {
+      this.ast.swapLocations(result, byref, result, this);
+      result.byref = true;  
+    }
     return result;
   },
 

test/debug.js

@@ -17,20 +17,17 @@
 const util = require('util');
 const parser = require("../src/index");
 const ast = parser.parseEval(`
-$foo = new Foo(
-  'constructor',
-  'bar',
-);
+$bar = &$foo;
 `, { 
     parser: {
       debug: true,
       php73: true,
       extractDoc: true
     },
-    /*ast: {
+    ast: {
       withPositions: true,
       withSource: true
-    }*/
+    }
   }
 );
 console.log(