ui: Update ArgTree type check

When there is an argument with a 'length' field, the logic
incorrectly assumes it is an ArgTreeArray instead of an ArgTreeMap.

This leads to crash here:
http://shortn/_aUD7nsSK71

https://screenshot.googleplex.com/AY52WpejUPfwXdE

This solution changes the type check.

An alternative solution would have been to create `type` fields in
both `ArgTreeMap` and `ArgTreeArray` and then check on those.

Bug: 218298947
Change-Id: I0fe662811dd1539ed344c5bed0c0d642a42f2baf

1 files changed, 2 insertions, 2 deletions

diff --git a/ui/src/common/arg_types.ts b/ui/src/common/arg_types.ts
index 6ca6a049a..864dc4b2b 100644
--- a/ui/src/common/arg_types.ts
+++ b/ui/src/common/arg_types.ts
@@ -22,9 +22,9 @@ export interface ArgsTreeMap {
 }
 
 export function isArgTreeArray(item: ArgsTree): item is ArgsTreeArray {
-  return typeof item === 'object' && item.length !== undefined;
+  return typeof item === 'object' && Array.isArray(item);
 }
 
 export function isArgTreeMap(item: ArgsTree): item is ArgsTreeMap {
-  return typeof item === 'object' && item.length === undefined;
+  return typeof item === 'object' && !Array.isArray(item);
 }