clawhdf5: FileEditor reports filters it cannot run as Error::Unsupported

A dataset whose filter this build cannot encode (scale-offset, N-Bit, SZIP;
a plugin filter the build lacks) failed with Error::Format("unsupported
filter: 6"), although the editor documents every refused edit as
Error::Unsupported, and the Python bindings raised ValueError rather than
NotImplementedError. Every edit now maps FormatError::UnsupportedFilter to
Error::Unsupported; the file is left untouched as before.

Test: edit_interop unencodable_filters_are_unsupported — h5py scale-offset
datasets (integer with chunks, integer never written, float D-scale):
Error::Unsupported naming the filter, and the file byte for byte unchanged.
Fails on the previous editor (Format(UnsupportedFilter(6))).

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>

crates/clawhdf5/src/edit/mod.rs

@@ -622,7 +622,7 @@ impl FileEditor {
         check_editable(&f)?;
         let sb = f.superblock().clone();
         let mut img = Image::new(f.as_bytes(), sb.offset_size, sb.length_size);
-        let r = op(&f, &mut img)?;
+        let r = op(&f, &mut img).map_err(unsupported_filter)?;
         if img.is_dirty() {
             if img.eoa() != img.old_eoa() {
                 set_superblock_eof(&mut img, &sb)?;
@@ -840,6 +840,20 @@ impl FileEditor {
     }
 }
 
+/// A filter this build cannot run (scale-offset, N-Bit and SZIP have no
+/// encoder; a plugin filter may be missing) is something the editor does not
+/// support, not a malformed file.
+fn unsupported_filter(e: Error) -> Error {
+    match e {
+        Error::Format(clawhdf5_format::error::FormatError::UnsupportedFilter(id)) => {
+            Error::Unsupported(format!(
+                "datasets with filter {id}, which this build cannot run"
+            ))
+        }
+        e => e,
+    }
+}
+
 /// libhdf5's checks before it opens a file for writing, and what this
 /// editor cannot keep consistent.
 fn check_editable(f: &File) -> Result<(), Error> {