Hi, thanks for reporting an issue. Could I get further information from you? For example, are you using multisite? What theme are you using? Is this error appearing in only one browser? Thanks in advance.
I’ve tried several themes such as generatepress, huemann or Twenty Seventeen. it’s not multisite. On Firefox, same things with error such as :
TypeError: e.capabilities is undefined
this.wp.editor</N</<.value/<@https://website.net/wp-content/plugins/gutenberg/editor/build/index.js?ver=1504771096:22:66406
n@https://website.net/wp-content/plugins/gutenberg/editor/build/index.js?ver=1504771096:6:21797
o@https://website.net/wp-content/plugins/gutenberg/editor/build/index.js?ver=1504771096:6:38312
this.wp.editor</N</<.value@https://website.net/wp-content/plugins/gutenberg/editor/build/index.js?ver=1504771096:22:66383
this.wp.editor</N</<.value@https://website.net/wp-content/plugins/gutenberg/editor/build/index.js?ver=1504771096:22:66477
d@https://website.net/wp-content/plugins/gutenberg/vendor/react-dom.min.912dc6cf.js:6:8044
c@https://website.net/wp-content/plugins/gutenberg/vendor/react-dom.min.912dc6cf.js:6:7921
k@https://website.net/wp-content/plugins/gutenberg/vendor/react-dom.min.912dc6cf.js:6:10250
u@https://website.net/wp-content/plugins/gutenberg/vendor/react-dom.min.912dc6cf.js:6:23202
p@https://website.net/wp-content/plugins/gutenberg/vendor/react-dom.min.912dc6cf.js:6:23668
v@https://website.net/wp-content/plugins/gutenberg/vendor/react-dom.min.912dc6cf.js:6:24215
k@https://website.net/wp-content/plugins/gutenberg/vendor/react-dom.min.912dc6cf.js:6:26488
E@https://website.net/wp-content/plugins/gutenberg/vendor/react-dom.min.912dc6cf.js:6:26060
Bu/p.enqueueSetState@https://website.net/wp-content/plugins/gutenberg/vendor/react-dom.min.912dc6cf.js:6:6195
n.prototype.setState@https://website.net/wp-content/plugins/gutenberg/vendor/react.min.c7397a88.js:4:3957
this.wp.components</t.a/</r</<.value@https://website.net/wp-content/plugins/gutenberg/components/build/index.js?ver=1504771096:6:188923
this.wp.components</t.a/</r</<.value/<@https://website.net/wp-content/plugins/gutenberg/components/build/index.js?ver=1504771096:6:189966
this.wp.components</E/</<@https://website.net/wp-content/plugins/gutenberg/components/build/index.js?ver=1504771096:6:146061
this.wp.components</E/<@https://website.net/wp-content/plugins/gutenberg/components/build/index.js?ver=1504771096:6:145931
this.wp.components</e.exports/u@https://website.net/wp-content/plugins/gutenberg/components/build/index.js?ver=1504771096:6:144182
Thank you for giving more details. I have gone through and reported this on GitHub where we are dealing with any issues for this project. https://github.com/WordPress/gutenberg/issues/2702 is the issue if you wish to follow on or add notes to the conversation.