Fix RuntimeShader example bug

Also make the error message explicit

Test: ColorFiltersMutateActivity doesn't crash on launch

Change-Id: I8fb5b9204badd141cd51f6149cdab0233f8264e3
diff --git a/libs/hwui/jni/Shader.cpp b/libs/hwui/jni/Shader.cpp
index 0f68376..e76aace 100644
--- a/libs/hwui/jni/Shader.cpp
+++ b/libs/hwui/jni/Shader.cpp
@@ -228,9 +228,12 @@
 
 static jlong RuntimeShader_createShaderFactory(JNIEnv* env, jobject, jstring sksl) {
     ScopedUtfChars strSksl(env, sksl);
-    sk_sp<SkRuntimeEffect> effect = std::get<0>(SkRuntimeEffect::Make(SkString(strSksl.c_str())));
-    ThrowIAE_IfNull(env, effect);
-
+    auto result = SkRuntimeEffect::Make(SkString(strSksl.c_str()));
+    sk_sp<SkRuntimeEffect> effect = std::get<0>(result);
+    if (!effect) {
+        const auto& err = std::get<1>(result);
+        doThrowIAE(env, err.c_str());
+    }
     return reinterpret_cast<jlong>(effect.release());
 }