Include a debug hint in snippet client error message. (#731)

diff --git a/mobly/controllers/android_device_lib/jsonrpc_client_base.py b/mobly/controllers/android_device_lib/jsonrpc_client_base.py
index 39e95b9..ebe0b67 100644
--- a/mobly/controllers/android_device_lib/jsonrpc_client_base.py
+++ b/mobly/controllers/android_device_lib/jsonrpc_client_base.py
@@ -93,7 +93,8 @@
 class ProtocolError(Error):
   """Raised when there is some error in exchanging data with server."""
   NO_RESPONSE_FROM_HANDSHAKE = 'No response from handshake.'
-  NO_RESPONSE_FROM_SERVER = 'No response from server.'
+  NO_RESPONSE_FROM_SERVER = ('No response from server. '
+                             'Check the device logcat for crashes.')
   MISMATCHED_API_ID = 'RPC request-response ID mismatch.'