Update BOINCUtils.kt

Fix warning print to log an exception. (do it in the right way).

android/BOINC/app/src/main/java/edu/berkeley/boinc/utils/BOINCUtils.kt

@@ -118,8 +118,9 @@ class TaskRunner<V>(private val callback: ((V) -> Unit)? , private val callable:
             callback?.invoke(result)
             result
         } catch (e: Exception) {
-            Log.d(Logging.TAG, e.message)
-            e.printStackTrace()
+            if (Logging.ERROR) {
+                Log.e(Logging.TAG, "BOINCUtils.TaskRunner error: ", e)
+            }
             throw e
         }
     }