server: Handle XSNWorkQueueDepthExceeded when the response is not a json

When the RPC API returns a non-json response, the XSNWorkQueueDepthExceeded
error can be derived.

server/app/com/xsn/explorer/services/XSNService.scala

@@ -443,13 +443,22 @@ class XSNServiceRPCImpl @Inject() (
               }
         }
 
+    maybe
+        .orElse {
           // if there is no result nor error, it is probably that the server returned non 200 status
-    maybe.orElse {
           Try(response.json)
               .toOption
               .flatMap { json => mapError(json, errorCodeMapper) }
               .map { e => Bad(e).accumulating }
         }
+        .orElse {
+          // if still there is no error, the response might not be a json
+          Try(response.body)
+              .collect {
+                case "Work queue depth exceeded" => Bad(XSNWorkQueueDepthExceeded).accumulating
+              }
+              .toOption
+        }
   }
 
   override val genesisBlockhash: Blockhash = explorerConfig.genesisBlock

server/test/com/xsn/explorer/services/XSNServiceRPCImplSpec.scala

@@ -8,8 +8,10 @@ import com.xsn.explorer.models.rpc.Masternode
 import org.mockito.ArgumentMatchers._
 import org.mockito.Mockito._
 import org.scalactic.{Bad, Good}
+import org.scalatest.concurrent.PatienceConfiguration.Timeout
 import org.scalatest.concurrent.ScalaFutures
 import org.scalatest.mockito.MockitoSugar
+import org.scalatest.time.{Seconds, Span}
 import org.scalatest.{MustMatchers, OptionValues, WordSpec}
 import play.api.libs.json.{JsNull, JsString, JsValue, Json}
 import play.api.libs.ws.{WSClient, WSRequest, WSResponse}
@@ -176,6 +178,19 @@ class XSNServiceRPCImplSpec extends WordSpec with MustMatchers with ScalaFutures
         result mustEqual Bad(XSNWorkQueueDepthExceeded).accumulating
       }
     }
+
+    "handle work queue depth exceeded (no json)" in {
+      val txid = createTransactionId("0834641a7d30d8a2d2b451617599670445ee94ed7736e146c13be260c576c641")
+
+      val responseBody = "Work queue depth exceeded"
+
+      mockRequestString(request, response)(500, responseBody)
+
+      val timeout = Timeout(Span(5, Seconds))
+      whenReady(service.getTransaction(txid), timeout) { result =>
+        result mustEqual Bad(XSNWorkQueueDepthExceeded).accumulating
+      }
+    }
   }
 
   "getRawTransaction" should {
@@ -571,8 +586,15 @@ class XSNServiceRPCImplSpec extends WordSpec with MustMatchers with ScalaFutures
   }
 
   private def mockRequest(request: WSRequest, response: WSResponse)(status: Int, body: JsValue) = {
-    when(response.status).thenReturn(200)
+    when(response.status).thenReturn(status)
     when(response.json).thenReturn(body)
+    when(response.body).thenReturn(body.toString())
+    when(request.post[String](anyString())(any())).thenReturn(Future.successful(response))
+  }
+
+  private def mockRequestString(request: WSRequest, response: WSResponse)(status: Int, body: String) = {
+    when(response.status).thenReturn(status)
+    when(response.body).thenReturn(body)
     when(request.post[String](anyString())(any())).thenReturn(Future.successful(response))
   }
 }