[Gradle, JS] Add more information on Gradle exception

^KT-41566 fixed

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/js/ir/KotlinJsBinaryContainer.kt

@@ -113,7 +113,12 @@ constructor(
             )
         }
 
-        throw GradleException("Library can be produced only for IR compiler")
+        throw GradleException(
+            """
+            Library can be produced only for IR compiler.
+            Use `kotlin.js.compiler=ir` Gradle property or `js(IR)` target declaration.
+            """
+        )
     }
 
     internal fun getIrBinaries(