fix: Un-nest Debug of errors holding only 'inner'

println!("{:#?}", toml::from_str::<i32>("").unwrap_err());

Before:

    Error {
        inner: Error {
            inner: TomlError {
                message: "invalid type: map, expected i32",
                raw: Some(
                    "",
                ),
                keys: [],
                span: Some(
                    0..0,
                ),
            },
        },
    }

After:

    TomlError {
        message: "invalid type: map, expected i32",
        raw: Some(
            "",
        ),
        keys: [],
        span: Some(
            0..0,
        ),
    }

crates/toml/src/de.rs

@@ -46,7 +46,7 @@ where
 }
 
 /// Errors that can occur when deserializing a type.
-#[derive(Debug, PartialEq, Eq, Clone)]
+#[derive(PartialEq, Eq, Clone)]
 pub struct Error {
     inner: crate::edit::de::Error,
 }
@@ -87,6 +87,12 @@ impl std::fmt::Display for Error {
     }
 }
 
+impl std::fmt::Debug for Error {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        self.inner.fmt(f)
+    }
+}
+
 impl std::error::Error for Error {}
 
 /// Deserialization TOML document

crates/toml/src/ser.rs

@@ -74,7 +74,7 @@ where
 }
 
 /// Errors that can occur when serializing a type.
-#[derive(Debug, Clone, PartialEq, Eq)]
+#[derive(Clone, PartialEq, Eq)]
 pub struct Error {
     pub(crate) inner: crate::edit::ser::Error,
 }
@@ -125,6 +125,12 @@ impl std::fmt::Display for Error {
     }
 }
 
+impl std::fmt::Debug for Error {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        self.inner.fmt(f)
+    }
+}
+
 impl std::error::Error for Error {}
 
 /// Serialization for TOML documents.

crates/toml_edit/src/de/mod.rs

@@ -21,7 +21,7 @@ use table_enum::TableEnumDeserializer;
 pub use value::ValueDeserializer;
 
 /// Errors that can occur when deserializing a type.
-#[derive(Debug, Clone, PartialEq, Eq)]
+#[derive(Clone, PartialEq, Eq)]
 pub struct Error {
     inner: crate::TomlError,
 }
@@ -71,6 +71,12 @@ impl std::fmt::Display for Error {
     }
 }
 
+impl std::fmt::Debug for Error {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        self.inner.fmt(f)
+    }
+}
+
 impl From<crate::TomlError> for Error {
     fn from(e: crate::TomlError) -> Error {
         Self { inner: e }