health-metrics/apk-size/app/configure.gradle: produce better error when sdk parsing fails

Author: dconeybe

health-metrics/apk-size/app/configure.gradle

@@ -24,7 +24,11 @@ repositories {
 if (project.hasProperty('sdks')) {
     project.android {
         sdks.split(',').each { sdk ->
-            def (groupId, artifactId, version) = sdk.split(':')
+            def sdkParts = sdk.split(':')
+            if (sdkParts.size() != 3) {
+                throw new GradleException("Invalid SDK format: '${sdk}'. Expected format: 'groupId:artifactId:version'")
+            }
+            def (groupId, artifactId, version) = sdkParts
             productFlavors.create(artifactId) {
                 dimension 'firebase'
             }