fix: Fixed proguard handling of custom gradle files

[bitsandfoxes]

Looks like there are plugins out there that modify the gradle template to list the proguard files like this

buildTypes {
        debug {
            minifyEnabled true

            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-unity.txt', 'proguard-user.txt'
            jniDebuggable true
        }
        release {
            minifyEnabled true

            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-unity.txt', 'proguard-user.txt'
            signingConfig signingConfigs.release
        }
    }

instead of consumerProguardFiles.

[bruno-garcia]

Is this breaking the build for the user? Should we gracefully degrade instead?

[bitsandfoxes]

The build doesn't break. The exception bubbles up and we catch and log it as an error.