Command PhaseScriptExecution failed with a nonzero exit code is a general message and because of this you may not find a solution that will work for your case. the best way to go about this is to get the root cause of this error.

Steps to get root cause

• Open Xcode

• Go to "Show the Report navigator"

• Click on the last build with the error

• Now you can be able to read the root error. For me the root error was flutterfire not configured. Well, it was but i had to re-authenticate.