fix: throws on invalid arguments for prepend/append, fixes #208

src/util/underscore.ts

@@ -120,6 +120,13 @@ export function identify<T> (val: T): T {
   return val
 }
 
+export function snakeCase (str: string) {
+  return str.replace(
+    /(\w?)([A-Z])/g,
+    (_, a, b) => (a ? a + '_' : '') + b.toLowerCase()
+  )
+}
+
 export function changeCase (str: string): string {
   const hasLowerCase = [...str].some(ch => ch >= 'a' && ch <= 'z')
   return hasLowerCase ? str.toUpperCase() : str.toLowerCase()