health-metrics/apk-size/app/configure.gradle: report clear error message when "sdk" string cannot be parsed.

Author: dconeybe

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

@@ -24,7 +24,14 @@ 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: '${sdk}'. " +
+                    "Expected format: 'groupId:artifactId:version' (sdks: '${sdks}')"
+                )
+            }
+            def (groupId, artifactId, version) = sdkParts
             productFlavors.create(artifactId) {
                 dimension 'firebase'
             }