Google Action apps crashes on some phrases and crashing after account linking

Question

Failed to parse Dialogflow response into AppResponse because of the empty speech response.

I'm always getting this issue on asking the same phrases of a particular intent. Inside the log I checked it is not triggering this intent. Also after account linking the app is crashing. Here is the log.

"responseMetadata": { "status": { "code": 10, "message": "Failed to parse Dialogflow response into AppResponse because of empty speech response", "details": [{ "@type": "type.googleapis.com/google.protobuf.Value", "value": "{\"id\":\"038a5fe6-7464-4fe3-83ea-8412e8c258d4\",\"timestamp\":\"2019-03-13T10:21:56.967Z\",\"lang\":\"en-gb\",\"result\":{},\"status\":{\"code\":206,\"errorType\":\"partial_content\",\"errorDetails\":\"Webhook call failed. Error: 500 Internal Server Error\"},\"sessionId\":\"ABwppHG-wf2qOaZ6G4x_uDV57cxrDj4XrFUUvNAUFYnlZuXKdwqBWlKGxnbbL5VBGP9fTqrYrTRvMYpK\"}" }] } } }.
{
 insertId:  "647th6f88zjhw"  
 labels: {…}  
 logName:  "projects/vguard-smart/logs/actions.googleapis.com%2Factions"  
 receiveTimestamp:  "2019-03-13T10:21:57.142635383Z"  
 resource: {…}  
 severity:  "DEBUG"  
 textPayload:  "Received response from agent with body: HTTP/1.1 200 OK
Server: nginx/1.13.6
Date: Wed, 13 Mar 2019 10:21:57 GMT
Content-Type: application/json;charset=UTF-8
Content-Length: 647
X-Cloud-Trace-Context: 4a627d76f2c02dc9c50afa1786f06ba7/7862509189815517582;o=0
Google-Actions-API-Version: 2
Assistant-Interaction-Error-Code: -1
Assistant-Interaction-Error-Message: Failed to parse Dialogflow response into AppResponse because of empty speech response
X-SHARD: shard-1
Via: 1.1 google
Alt-Svc: clear

{
  "responseMetadata": {
    "status": {
      "code": 10,
      "message": "Failed to parse Dialogflow response into AppResponse because of empty speech response",
      "details": [{
        "@type": "type.googleapis.com/google.protobuf.Value",
        "value": "{\"id\":\"038a5fe6-7464-4fe3-83ea-8412e8c258d4\",\"timestamp\":\"2019-03-13T10:21:56.967Z\",\"lang\":\"en-gb\",\"result\":{},\"status\":{\"code\":206,\"errorType\":\"partial_content\",\"errorDetails\":\"Webhook call failed. Error: 500 Internal Server Error\"},\"sessionId\":\"ABwppHG-wf2qOaZ6G4x_uDV57cxrDj4XrFUUvNAUFYnlZuXKdwqBWlKGxnbbL5VBGP9fTqrYrTRvMYpK\"}"
      }]
    }
  }
}."  
 timestamp:  "2019-03-13T10:21:57.110708894Z"  
 trace:  "projects/459929986218/traces/ABwppHG-wf2qOaZ6G4x_uDV57cxrDj4XrFUUvNAUFYnlZuXKdwqBWlKGxnbbL5VBGP9fTqrYrTRvMYpK"  
}