fix: Check for empty array in thrasos.RenderInfo.addElemSpacing_ (#6211)

* fix: Check for undefined value in InputRow.measure

* Revert "fix: Check for undefined value in InputRow.measure"

This reverts commit f2e57c06ad.

* fix: thrasos: don't push elements if array is empty

- Use same array length check as geras renderer does

core/renderers/thrasos/info.js

@@ -82,6 +82,9 @@ class RenderInfo extends BaseRenderInfo {
         row.elements.push(new InRowSpacer(
             this.constants_, this.getInRowSpacing_(null, oldElems[0])));
       }
+      if (!oldElems.length) {
+        continue;
+      }
       for (let e = 0; e < oldElems.length - 1; e++) {
         row.elements.push(oldElems[e]);
         const spacing = this.getInRowSpacing_(oldElems[e], oldElems[e + 1]);