switch DEBUG_LOG to string handling

src/lib/truthyString.ts

@@ -1,4 +1,7 @@
 export function isTruthy(value: string | number | boolean | null | undefined): boolean {
+  if (value === null || value === undefined) {
+    return false;
+  }
   if (typeof value === 'string') {
     return value.toLowerCase() === 'true' || !!+value; // here we parse to number first
   }