If getters throw, replace value with a placeholder

Summary:
Currently, if you try to inspect globals in the debugger and they have
properties that throw exceptions, the app redscreens.  In particular,
inspecting any function triggers the bug because of `arguments` and
`caller`.

This diff catches the exception and shows a placeholder instead.

Changelog: [Internal]

Reviewed By: mhorowitz

Differential Revision: D18664765

fbshipit-source-id: 0c662f3d97b21a29c57a1dd724e63d17a3b4e263

ReactCommon/hermes/inspector/chrome/Connection.cpp

@@ -646,9 +646,21 @@ Connection::Impl::makePropsFromValue(
       m::runtime::PropertyDescriptor desc;
       desc.name = propName.utf8(runtime);
 
-      jsi::Value propValue = obj.getProperty(runtime, propName);
-      desc.value = m::runtime::makeRemoteObject(
-          runtime, propValue, objTable_, objectGroup);
+      try {
+        // Currently, we fetch the property even if it runs code.
+        // Chrome instead detects getters and makes you click to invoke.
+        jsi::Value propValue = obj.getProperty(runtime, propName);
+        desc.value = m::runtime::makeRemoteObject(
+            runtime, propValue, objTable_, objectGroup);
+      } catch (const jsi::JSError &err) {
+        // We fetched a property with a getter that threw. Show a placeholder.
+        // We could have added additional info, but the UI quickly gets messy.
+        desc.value = m::runtime::makeRemoteObject(
+            runtime,
+            jsi::String::createFromUtf8(runtime, "(Exception)"),
+            objTable_,
+            objectGroup);
+      }
 
       result.emplace_back(std::move(desc));
     }