category does not exist on safari with nodebb 1.2.1

[mango]

when I post, if choose the first category, it seem something error.give me "category does not exist"
if I choose the second category,no this error,but zhe post will appear to first category ,this is wrong.
only on safari.I test my nodebb :sns.widora.io and community.nodebb.org.
that seems no this error on chrome.

[mango]

I git clone v1.x.x branch.
today I git reset --hard fdd8514, then work OK!