don't provide both a source and embed it into the Display impl

crates/symbolicator/src/services/download/mod.rs

@@ -46,11 +46,10 @@ pub enum DownloadError {
     Write(#[source] std::io::Error),
     #[error("download was cancelled")]
     Canceled,
-    #[error("failed to fetch data from GCS: {0}")]
+    #[error("failed to fetch data from GCS")]
     Gcs(#[from] gcs::GcsError),
-    #[error("failed to fetch data from Sentry: {0}")]
+    #[error("failed to fetch data from Sentry")]
     Sentry(#[from] sentry::SentryError),
-    #[allow(unused)]
     #[error("failed to fetch data from S3")]
     S3(#[from] s3::S3Error),
     /// Typically means the initial HEAD request received a non-200, non-400 response.
@@ -59,6 +58,17 @@ pub enum DownloadError {
     Rejected(StatusCode),
 }
 
+impl DownloadError {
+    pub fn for_cache(&self) -> String {
+        match self {
+            DownloadError::Gcs(inner) => format!("{}: {}", self, inner),
+            DownloadError::Sentry(inner) => format!("{}: {}", self, inner),
+            DownloadError::S3(inner) => format!("{}: {}", self, inner),
+            _ => format!("{}", self),
+        }
+    }
+}
+
 /// Completion status of a successful download request.
 #[derive(Debug, Clone, Eq, PartialEq, Hash)]
 pub enum DownloadStatus {

crates/symbolicator/src/services/objects/data_cache.rs

@@ -169,7 +169,7 @@ impl CacheItemRequest for FetchFileDataRequest {
 
                 Err(e) => {
                     log::error!("Error while downloading file: {}", LogError(&e));
-                    return Ok(CacheStatus::Malformed(e.to_string()));
+                    return Ok(CacheStatus::Malformed(e.for_cache()));
                 }
 
                 Ok(DownloadStatus::Completed) => {