error building app bundle: Could not get unknown property 'release' for SigningConfig

I'm getting this error when trying to build the app bundle.I went to line 56 and checked and my line looks like this:

56. signingConfig signingConfigs.release

and here is error from terminal

`Gradle task bundleRelease failed with exit code 1 (base) juliapak@julias-MacBook-Pro phonecallforgirls % flutter build appbundle

Building with sound null safety

FAILURE: Build failed with an exception.

• Where:
  Build file '/Users/juliapak/Documents/phonecallforgirls/android/app/build.gradle' line: 56

• What went wrong:
  A problem occurred evaluating project ':app'.

Could not get unknown property 'release' for SigningConfig container of type org.gradle.api.internal.FactoryNamedDomainObjectContainer.

• Try:
  Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

• Get more help at https://help.gradle.org

BUILD FAILED in 737ms
Running Gradle task 'bundleRelease'...
Running Gradle task 'bundleRelease'... Done 1,400ms Gradle task bundleRelease failed with exit code 1 (base) juliapak@julias-MacBook-Pro phonecallforgirls % `