This is a common and longstanding community crash on Mac. Users have not provided descriptions when they crash, so additional information is currently not available. A log file is attached.
Callstack from Log
Editor crashes with a DispatchEventToHandlers() error
The Scalar Parameter's value is set to 1
Update: a user provided the following:
"100% reproducible: - On macOS Sierra, turn on Chinese Pinyin input. - Open Material Editor and create a Constant Value in Graph panel. - In Detail panel, change the value to 1.0. - Crash. Seems UE editor does not like a mix of Piyin with its entry boxes."
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-46405 in the post.