
Fixes https://github.com/flutter/devtools/issues/8905 Based on the stacktrace in https://github.com/flutter/devtools/issues/8905: * This call to `renderObject` can throw a null-exception:39b4951f8f/packages/flutter/lib/src/widgets/framework.dart (L3745)
* That exception is thrown here:39b4951f8f/packages/flutter/lib/src/widgets/framework.dart (L6534)
I've been unable to figure out a way to get into a state that reproduces this. Instead, this PR simply handles the exception and returns `null` (because we already gracefully handle the case where the `renderObject` is `null`.