Prevent 0 flag count from rendering in DOM

Preact exhibits funny behavior for inline conditionals that don’t resolve to an actual boolean value. When the flagCount variable is 0 it renders the conditional statement directly in the dom. Casting to a boolean prevents this.

src/sidebar/components/moderation-banner.js

@@ -75,7 +75,7 @@ function ModerationBanner({ annotation, api, flash }) {
   }
   return (
     <div className={bannerClasses}>
-      {flagCount && !annotation.hidden && (
+      {Boolean(flagCount) && !annotation.hidden && (
         <span>Flagged for review x{flagCount}</span>
       )}
       {annotation.hidden && (