Same for me, after Update to: 3.0.140
Does anybody encounter also analogue problem with mapmarker?
I've just tryed to open the field and:
Fatal Error: Uncaught Error: Call to a member function prepend() on null in /var/www/www____/wire/core/Fields.php:1066
Stack trace: #0 /var/www/mywww/wire/modules/Process/ProcessField/ProcessField.module(1412): ProcessWire\Fields->getCompatibleFieldtypes(Object(ProcessWire\Field)) #1 /var/www/mywww/wire/core/Wire.php(380): ProcessWire\ProcessField->___buildEditFormBasics() #2 /var/www/mywww/wire/core/WireHooks.php(813): ProcessWire\Wire->_callMethod('___buildEditFor...', Array) #3 /var/www/mywwwit/wire/core/Wire.php(442): ProcessWire\WireHooks->runHooks(Object(ProcessWire\ProcessField), 'buildEditFormBa...', Array) #4 /var/www/mywww/wire/modules/Process/ProcessField/ProcessField.module(1020): ProcessWire\Wire->__call('buildEditFormBa...', Array) #5 /var/www/mywww/wire/core/Wire.php(380): ProcessWire\ProcessField->___buildEditForm() #6 /var/www/mywww/wire/core/WireHooks.php(813): ProcessWire\Wire->_callMethod('___buildEditFor...', Array) #7 /var/www/mywww/ (line 1066 of /var/www/www.440-hz.it/wire/core/Fields.php)