don't do any replacement if theres an empty string

Author: JS00001

lib/ExpensiMark.ts

@@ -951,6 +951,10 @@ export default class ExpensiMark {
      * If not provided, all available rules will be applied. If provided, the rules in the array will be skipped.
      */
     replace(text: string, {filterRules = [], shouldEscapeText = true, shouldKeepRawInput = false, disabledRules = [], extras = EXTRAS_DEFAULT}: ReplaceOptions = {}): string {
+        if (!text) {
+            return '';
+        }
+
         // This ensures that any html the user puts into the comment field shows as raw html
         let replacedText = shouldEscapeText ? Utils.escapeText(text) : text;
         const rules = this.getHtmlRuleset(filterRules, disabledRules, shouldKeepRawInput);
@@ -987,6 +991,7 @@ export default class ExpensiMark {
     /**
      * Checks matched URLs for validity and replace valid links with html elements
      */
+    // TODO
     modifyTextForUrlLinks(regex: RegExp, textToCheck: string, replacement: ReplacementFn): string {
         let match = regex.exec(textToCheck);
         let replacedText = '';