Switch to using CustomError because a boxed StdError is not Send.

src/error/error.rs

@@ -0,0 +1,45 @@
+#[derive(Debug)]
+pub(crate) enum CustomError {
+    Static(&'static str),
+    IO(std::io::Error),
+    TomlSerialize(toml::ser::Error),
+    TomlDeserialize(toml::de::Error),
+    WalkDir(walkdir::Error),
+    Tokio(tokio::task::JoinError),
+}
+
+impl From<std::io::Error> for CustomError {
+    fn from(value: std::io::Error) -> Self {
+        CustomError::IO(value)
+    }
+}
+
+impl From<&'static str> for CustomError {
+    fn from(value: &'static str) -> Self {
+        CustomError::Static(value)
+    }
+}
+
+impl From<toml::ser::Error> for CustomError {
+    fn from(value: toml::ser::Error) -> Self {
+        CustomError::TomlSerialize(value)
+    }
+}
+
+impl From<toml::de::Error> for CustomError {
+    fn from(value: toml::de::Error) -> Self {
+        CustomError::TomlDeserialize(value)
+    }
+}
+
+impl From<walkdir::Error> for CustomError {
+    fn from(value: walkdir::Error) -> Self {
+        CustomError::WalkDir(value)
+    }
+}
+
+impl From<tokio::task::JoinError> for CustomError {
+    fn from(value: tokio::task::JoinError) -> Self {
+        CustomError::Tokio(value)
+    }
+}

src/error/mod.rs

@@ -0,0 +1,3 @@
+#[allow(clippy::module_inception)]
+mod error;
+pub(crate) use error::CustomError;