Fix integer/string conversion when string is empty

Author: GuillaumeGomez

src/ast.js

@@ -35,15 +35,14 @@ function replaceVariable(elem, variables, functionArgs, forceVariableAsString, e
     if (associatedValue instanceof Element) {
         // Nothing to be done in here.
         return associatedValue;
-    } else if (['number', 'string', 'boolean'].includes(typeof associatedValue)) {
-        if (typeof associatedValue === 'boolean') {
-            return new IdentElement(
-                associatedValue.toString(), startPos, endPos, lineNumber);
-        } else if (typeof associatedValue === 'number' ||
-            // eslint-disable-next-line no-extra-parens
-            (!forceVariableAsString && matchInteger(associatedValue) === true)) {
-            return new NumberElement(associatedValue, startPos, endPos, lineNumber);
-        }
+    } else if (typeof associatedValue === 'boolean') {
+        return new IdentElement(
+            associatedValue.toString(), startPos, endPos, lineNumber);
+    } else if (typeof associatedValue === 'number' ||
+        // eslint-disable-next-line no-extra-parens
+        (!forceVariableAsString && matchInteger(associatedValue) === true)) {
+        return new NumberElement(associatedValue, startPos, endPos, lineNumber);
+    } else if (typeof associatedValue === 'string') {
         return new StringElement(
             associatedValue,
             startPos,

src/parser.js

@@ -21,7 +21,7 @@ function isLetter(c) {
 function matchInteger(s) {
     if (typeof s === 'number' || s instanceof Number) {
         return true;
-    } else if (typeof s === 'string' || s instanceof String) {
+    } else if ((typeof s === 'string' || s instanceof String) && s.length !== 0) {
         for (let i = s.length - 1; i >= 0; --i) {
             if (!isNumber(s.charAt(i))) {
                 return false;