I get a similar error when using Visual Composer plug-in. The Visual Composer support group quickly isolated the issue as an Ultimate Member issue. I provided details on the error I see in the Chrome Dev Console as well as a video showing the issue with UM plug-in enabled and then disabled (see link below to my posting). Only get errors when UM plug-in is active. Still waiting for a response on my issue. Sorry I cannot help with your issue but hopefully if they resolve one, they resolve the other.
Very long list of issues in the Dev Console. Here are but 2 issues I only see when UM plug-in is active (no errors if I inactivate the UM plug-in).
load-scripts.php?c=0&load[chunk_0]=underscore,utils,jquery-core,jquery-migrate,moxiejs,plupload,wp-codemirror&ver=5.4.2:12 JQMIGRATE: Migrate is installed, version 1.4.1
jquery-migrate.min.js,qver=1.4.1.pagespeed.jm.C2obERNcWh.js:1 JQMIGRATE: Migrate is installed, version 1.4.1
wp.bundle.js?ver=29.0:2 failed to parse json RangeError: Maximum call stack size exceeded
wp.bundle.js?ver=29.0:2 failed to parse json RangeError: Maximum call stack size exceeded
Link to my post.