Validate Shell Command Input Argument Vector

A fuzz test revealed that the input argument list vector
was not being validated for size, leading to a out-of-bounds
read for an empty vector.

Bug: 154500963
Test: Trivial fix
Change-Id: I8186d33eb72c036263fd0bd1b693a5d44ffb3a9f
diff --git a/services/sensorservice/SensorService.cpp b/services/sensorservice/SensorService.cpp
index ffcd0a0..2b4fd7f 100644
--- a/services/sensorservice/SensorService.cpp
+++ b/services/sensorservice/SensorService.cpp
@@ -699,6 +699,9 @@
     if (!checkCallingPermission(sManageSensorsPermission, nullptr, nullptr)) {
         return PERMISSION_DENIED;
     }
+    if (args.size() == 0) {
+      return BAD_INDEX;
+    }
     if (in == BAD_TYPE || out == BAD_TYPE || err == BAD_TYPE) {
         return BAD_VALUE;
     }