Don't -ping when extracting file details (workaround for imagemagick json bug)

src/discover/magick.rs

@@ -189,7 +189,7 @@ where
         "magick",
         &[
             "convert".as_ref(),
-            "-ping".as_ref(),
+            // "-ping".as_ref(), // re-enable -ping after imagemagick fix
             input_file.as_os_str(),
             "JSON:".as_ref(),
         ],
@@ -197,7 +197,7 @@ where
         timeout,
     )?
     .read()
-    .into_vec()
+    .into_string()
     .await;
 
     input_file.cleanup().await.map_err(MagickError::Cleanup)?;
@@ -213,7 +213,7 @@ where
     }
 
     let output: Vec<MagickDiscovery> =
-        serde_json::from_slice(&output).map_err(MagickError::Json)?;
+        serde_json::from_str(&output).map_err(|e| MagickError::Json(output, e))?;
 
     parse_discovery(output).map_err(MagickError::Discover)
 }

src/magick.rs

@@ -17,8 +17,8 @@ pub(crate) enum MagickError {
     #[error("Error in imagemagick process")]
     Process(#[source] ProcessError),
 
-    #[error("Invalid output format")]
-    Json(#[source] serde_json::Error),
+    #[error("Invalid output format: {0}")]
+    Json(String, #[source] serde_json::Error),
 
     #[error("Error writing bytes")]
     Write(#[source] std::io::Error),
@@ -62,7 +62,7 @@ impl MagickError {
         match self {
             Self::CommandFailed(_) => ErrorCode::COMMAND_FAILURE,
             Self::Process(e) => e.error_code(),
-            Self::Json(_)
+            Self::Json(_, _)
             | Self::Write(_)
             | Self::CreateFile(_)
             | Self::CreateDir(_)