JS error on search page after viewing 404 trace

[tiffon]

Description

Navigating from a trace page that is 404 (trace not found) to the search page results in a JS error.

Steps to reproduce the issue:

1. Visit a trace page that does not exist, e.g. /trace/000
2. Click the "Search" button in the top nav

Describe the results you received:

The page does not change and the following JS error is logged:

Uncaught TypeError: Cannot read property 'length' of undefined
    at o (search.js:43)
    at Array.map (<anonymous>)
    at a (search.js:88)
    at index.js:209
    at get-last-xform-cacher.js:38
    at Function.a [as mapToProps] (index.js:232)
    at r (wrapMapToProps.js:43)
    at Function.r.mapToProps (wrapMapToProps.js:52)
    at r (wrapMapToProps.js:43)
    at o (selectorFactory.js:26)

Describe the results you expected:

The search page is presented without error.