create gather without a prompt

lib/tasks/cognigy/speech-config.js

@@ -51,13 +51,23 @@ class SpeechConfig extends Emitter {
     const minBargeinWordCount = speechBargein ? (bargein.minWordCount || 1) : 0;
     const {interDigitTimeout = 0, maxDigits, minDigits = 1, submitDigit} = (opts.dtmf || {});
     const {noInputTimeout, noInputRetries, noInputSpeech, noInputUrl} = (opts.user || {});
-    const sayConfig = {
-      text: textPrompt,
-      synthesizer: opts.synthesizer
-    };
-    const playConfig = {
-      url: urlPrompt
-    };
+
+    let sayConfig;
+    let playConfig;
+
+    if (textPrompt) {
+      sayConfig = {
+        text: textPrompt,
+        synthesizer: opts.synthesizer
+      };
+    }
+
+    if (urlPrompt) {
+      playConfig = {
+        url: urlPrompt
+      };
+    }
+
     const config = {
       input,
       listenDuringPrompt: speechBargein,