Can you please provide us with the log file and JVM dump to analyse the issue.
Since there is an issue with the current theme applied, you can continue to work with the project by removing this applied theme.
Steps below should help.
1. Create a new workspace and import this project.
To import the project goto File -> Import -> Other -> General -> Existing Projects to workspace.
Select the root folder of the project.
2. Goto project properties -> Flec Theme and select the default theme (spark / halo based on the sdk version).
You can now continue to work with the project.