run(): Remove unused assignment to `email_eid`HEADmaster

This blog post by Dimitri Merejkowsky clued me into the fact that I had
incorrectly ignored a compiler warning about an unused assignment:
https://dmerej.info/blog/post/awesome-rust-warnings/#the-useless-mutation

When I wrote that line, I didn't realise you could declare an
uninitialised variable, and definitely didn't get what the compiler
meant when it told me:

    warning: value assigned to `email_eid` is never read
       --> src/main.rs:102:9
        |
    102 |     let mut email_eid = String::new();
        |         ^^^^^^^^^^^^^
        |
        = note: `#[warn(unused_assignments)]` on by default
        = help: maybe it is overwritten before being read?

so I ignored the warning.

1 files changed, 1 insertions, 3 deletions

diff --git a/src/main.rs b/src/main.rs
index 3d508f7..88d6ec3 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -99,9 +99,7 @@ async fn run() -> anyhow::Result<()> {
 
     let mut action_opt: Option<EventResponseStatus> = None;
     let mut should_read_email = false;
-
-    #[allow(unused_assignments)]
-    let mut email_eid = String::new();
+    let email_eid;
 
     let mut event_ids = Vec::new();
     let mut is_verbose = false;