Merge #146: Feature guard write_err import

c16b68a Feature guard write_err import (Tobin C. Harding)

Pull request description:

  We only use the `write_err` macro when the "alloc" feature is enabled, the import statement should be feature guarded.

  Clears a clippy warning.

ACKs for top commit:
  apoelstra:
    ACK c16b68a

Tree-SHA512: b274697f24abc0d3376f29e7ba8162e959b3ef4c449e061e662e94d06c94873116f7db96dc1fb702b440d9fc3d2bfb93e291ea5d631c9a5038cb7cea76913eef

Author: apoelstra

src/lib.rs

@@ -142,6 +142,7 @@ pub mod segwit;
 use alloc::{string::String, vec::Vec};
 use core::fmt;
 
+#[cfg(feature = "alloc")]
 use crate::error::write_err;
 #[cfg(doc)]
 use crate::primitives::decode::CheckedHrpstring;