hidl_error_test: add failure code

Only 1 is considered a good failure. When the code is aborted or
returns another unexpected failure, this leads to confusing messages.

Bug: N/A
Test: hidl_error_test
Change-Id: I2e135ffc609542fdc674ff7dc8be8fc40d2ec6ea
diff --git a/test/error_test/hidl_error_test.sh b/test/error_test/hidl_error_test.sh
index d747776..d566488 100755
--- a/test/error_test/hidl_error_test.sh
+++ b/test/error_test/hidl_error_test.sh
@@ -26,7 +26,7 @@
   fi
 
   if [ $command_fails -ne 1 ]; then
-    echo "error: $package test did not fail"
+    echo "error: $package test finished with code $command_fails, but expected 1"
     exit 1
   fi