Improve error handling (#33)

* refactor: improve error handling

* fix: specify bind address instead of port

* fix: remove temporary testing file

* fix(errors): change error names to snake_case

* refactor(errors): split indexing error types, remove unused errors

* feat: add env variable checking at program start

This just checks whether the enviroment variables exist and can
parse to the given type and gives a warning if they can't. This
should prevent cases where the program fails at runtime due to
checking an environment variable that doesn't exist.

src/file_hosting/mod.rs

@@ -18,10 +18,8 @@ pub use delete::DeleteFileData;
 
 #[derive(Error, Debug)]
 pub enum FileHostingError {
-    #[error("Error while accessing the data from remote")]
-    RemoteWebsiteError(#[from] reqwest::Error),
-    #[error("Error while serializing or deserializing JSON")]
-    SerDeError(#[from] serde_json::Error),
+    #[error("Error while accessing the data from backblaze")]
+    BackblazeError(#[from] reqwest::Error),
 }
 
 #[cfg(test)]