astwalker improved

libs/remix-debug/src/source/astWalker.js

@@ -21,7 +21,8 @@ AstWalker.prototype.walk = function (ast, callback) {
   if (!('*' in callback)) {
     callback['*'] = function () { return true }
   }
-  const nodes = ast.nodes || (ast.body && ast.body.statements) || ast.declarations
+  if(ast){
+    const nodes = ast.nodes || (ast.body && ast.body.statements) || ast.declarations || []
     if(ast.body && ast.initializationExpression) // 'for' loop handling
       nodes.push(ast.initializationExpression)
     if (manageCallBack(ast, callback) && nodes && nodes.length > 0) {
@@ -31,6 +32,7 @@ AstWalker.prototype.walk = function (ast, callback) {
       }
     }
   }
+}
 
 /**
  * walk the given @astList