Zed union values rendered blank in Detail window about zui

[philrz]

@SoftTools59654: I think I've figured out what's probably triggering the bug you saw. I couldn't initially reproduce the problem using only the data shown in your screenshot or other random data sets I had on hand. But in thinking about the kinds of Zed values that have caused problems in the past, in this attached video I happened to reproduce the problem successfully at Zui commit ca6ddd3 using this sample data.csv:

Index,Customer Id
1966079,54b0eFA66A2fE15
1900543,fE24fDD0D042fFE
123,456

Repro.mp4

What seems to be important in reproducing the problem is that across the data set the Customer Id field has values of both string type and numeric type (i.e., the final row in my data.csv triggers the problem), such that after fuse is applied the overall data type for Customer Id becomes a Zed union data type.

Therefore it looks like we probably have a Zui bug here we can fix that's specific to rendering values of union types. If you've seen this same effect with other types, please do share the details so we can fix those as well.