FEAT: Remove InsertError again

try_insert has a capacity error, but panics if the index is out of
bounds.

src/array_string.rs

@@ -12,6 +12,7 @@ use std::slice;
 use array::{Array, ArrayExt};
 use array::Index;
 use CapacityError;
+use errors::PubCrateNew;
 use odds::char::encode_utf8;
 
 #[cfg(feature="serde-1")]