Error in downloading old experiments

[cjqian]

When downloading an old experiment (for example, https://deliberate-lab.appspot.com/#/e/23c877c9-9b48-4669-9970-745a4faac33a):

The interface shows an infinite loading; this is in the console:

bundle.js:1755 Uncaught (in promise) TypeError: Cannot convert undefined or null to object
at Function.keys ()
at bundle.js:1755:8208
at Array.forEach ()
at bundle.js:1755:8179
at Array.forEach ()
at Nj (bundle.js:1755:8151)
at bundle.js:1755:28061
at Array.forEach ()
at bundle.js:1755:27794
at Vj. (bundle.js:1755:28356)

The interface should either throw an error to show that the experiment cannot be deleted, or ignore undefined objects / try to download what it can (preferred).

[cjqian]

Note: This appears to be specific to the chip negotiation experiments.