make the number normalization more robust

when a number field has its value removed in the UI, the value will be reset to the default, but will instead be the empty string. Empty strings in JS are parsed as 0, which is a problem for values, that may not be 0.

extensions/vier-cognitive-voice-gateway/src/helpers/util.ts

@@ -110,7 +110,11 @@ function toNumberOrUndefined(numeric: number | string | undefined | null): numbe
     return undefined;
   }
   if (typeof numeric === 'string') {
-    const parsedNumber = Number(numeric);
+    const trimmed = numeric.trim()
+    if (trimmed === '') {
+      return undefined
+    }
+    const parsedNumber = Number(trimmed);
     return isNaN(parsedNumber) ? undefined : parsedNumber;
   }
   if (typeof numeric !== 'number') {

extensions/vier-cognitive-voice-gateway/src/nodes/promptForNumber.ts

@@ -123,6 +123,7 @@ export const promptForNumberNode = createNodeDescriptor({
       });
     }
 
+    const maxDigits = normalizeInteger(config.maxDigits, 1, undefined);
     const payload = {
       status: 'prompt',
       timeout: convertDurationFromSecondsToMillis(config.timeout),
@@ -132,8 +133,8 @@ export const promptForNumberNode = createNodeDescriptor({
       type: {
         name: 'Number',
         submitInputs: submitInputs,
-        minDigits: normalizeInteger(config.minDigits, undefined, undefined),
-        maxDigits: normalizeInteger(config.maxDigits, undefined, undefined),
+        minDigits: normalizeInteger(config.minDigits, undefined, maxDigits),
+        maxDigits: maxDigits,
       },
     };
     api.say(config.text, payload);