ubiquity crashes in start_slideshow - Could not locate webkit_web_context_get_default: 'webkit_web_context_get_default': /usr/lib/x86_64-linux-gnu/libjavascriptcoregtk-4.0.so.18: undefined symbol: webkit_web_context_get_default

The Ubuntu Error Tracker has been receiving reports about a problem regarding ubiquity. This problem was most recently seen with package version 18.04.2, the problem page at https://errors.ubuntu.com/problem/f8cb12490c4fbefafd401bb31ee43efc0166b8cc contains more details, including versions of packages affected, stacktrace or traceback, and individual crash reports.
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Traceback (most recent call last):
  File "/usr/lib/ubiquity/bin/ubiquity", line 655, in <module>
    main(oem_config)
  File "/usr/lib/ubiquity/bin/ubiquity", line 641, in main
    install(query=options.query)
  File "/usr/lib/ubiquity/bin/ubiquity", line 274, in install
    ret = wizard.run()
  File "/usr/lib/ubiquity/ubiquity/frontend/gtk_ui.py", line 818, in run
    self.start_slideshow()
  File "/usr/lib/ubiquity/ubiquity/frontend/gtk_ui.py", line 898, in start_slideshow
    context = WebKit2.WebContext.get_default()
GLib.GError: g-invoke-error-quark: Could not locate webkit_web_context_get_default: 'webkit_web_context_get_default': /usr/lib/x86_64-linux-gnu/libjavascriptcoregtk-4.0.so.18: undefined symbol: webkit_web_context_get_default (1)