Fix file writing (#34)

I worked quite hard yesterday on the previous commit and convinced myself of a
non-thing. This resulted in there being no logs written to disk.

Signed-off-by: Brian L. Troutwine <brian@troutwine.us>

Author: blt

Cargo.lock

@@ -1,6 +1,6 @@
 [package]
 name = "file_gen"
-version = "0.3.0"
+version = "0.3.1"
 authors = ["Brian L. Troutwine <brian@troutwine.us>"]
 edition = "2018"
 license = "MIT"

Cargo.toml

@@ -197,10 +197,7 @@ impl Log {
             self.rate_limiter.until_n_ready(*nz_bytes).await?;
 
             {
-                // NOTE we intentionally do not wait on the write to
-                // complete. The rate_limiter is the sole governor of whether
-                // writes are attempted, avoiding coordinated omission.
-                let _ = fp.write(block);
+                fp.write(block).await?;
                 counter!("bytes_written", block.len() as u64, &labels);
                 counter!("lines_written", 1, &labels);