Uncaught TypeError: Cannot read property 'sort' of undefined

[mateja176]

?module=416&group=:1 Uncaught TypeError: Cannot read property 'sort' of undefined
    at u (?module=416&group=:1)
    at u (?module=416&group=:1)
    at FileReader.n.onload (?module=416&group=:1)
u @ ?module=416&group=:1
u @ ?module=416&group=:1
n.onload @ ?module=416&group=:1
load (async)
s @ ?module=416&group=:1
executeOnChange @ ?module=416&group=:1
s @ ?module=416&group=:1
s.invokeGuardedCallback @ ?module=416&group=:1
i @ ?module=416&group=:1
a @ ?module=416&group=:1
p @ ?module=416&group=:1
f @ ?module=416&group=:1
r @ ?module=416&group=:1
processEventQueue @ ?module=416&group=:1
r @ ?module=416&group=:1
handleTopLevel @ ?module=416&group=:1
s @ ?module=416&group=:1
perform @ ?module=416&group=:1
batchedUpdates @ ?module=416&group=:1
s @ ?module=416&group=:1
dispatchEvent @ ?module=416&group=:1

The error happened while importing a file which was output by the command source-map-explorer --json stats.json 'build/static/js/*.js'