Reduce build warnings (#712)

* Add annotations to and reformat SearchableRepositoryViewModel.kt

* Address build warnings other than meaningful deprecations

* Deal with warnings in UserPreference.kt

1 files changed, 1 insertions, 0 deletions

diff --git a/build.gradle b/build.gradle
index 15c49cf0..2120b6f9 100644
--- a/build.gradle
+++ b/build.gradle
@@ -65,6 +65,7 @@ subprojects {
     tasks.withType(org.jetbrains.kotlin.gradle.tasks.KotlinCompile) {
         kotlinOptions {
             jvmTarget = '1.8'
+            freeCompilerArgs += "-Xopt-in=kotlin.RequiresOptIn"
         }
     }
 }