Tolerate missing LZW end-of-information marker

Some TIFF encoders (e.g., UK Environment Agency LiDAR DTM tiles)
omit the LZW end-of-information code. Previously `LZWReader::read`
returned UnexpectedEof on `NoProgress` even when that same call had
already decoded valid pixel bytes — discarding them and failing the
whole image.

This change returns any output produced in a `NoProgress` call.
A subsequent read that produces zero output still errors, so a
genuinely truncated stream is still caught by `read_exact`.

Matches the LZW portion of image-rs#386 (dropped upstream
pending a wider decoder-API rework). Carried by madri until upstream
lands an equivalent fix.

Author: karijd

src/decoder/stream.rs

@@ -170,6 +170,15 @@ impl<R: Read> Read for LZWReader<R> {
                     }
                 }
                 Ok(weezl::LzwStatus::NoProgress) => {
+                    // Some TIFF encoders omit the LZW end-of-information code.
+                    // If this call produced output, return it; a subsequent read
+                    // with zero progress still errors, so genuinely short streams
+                    // are still caught by `read_exact` downstream.
+                    // See image-rs/image-tiff#386 (fix dropped upstream pending
+                    // a wider decoder-API rework).
+                    if result.consumed_out > 0 {
+                        return Ok(result.consumed_out);
+                    }
                     return Err(io::Error::new(
                         io::ErrorKind::UnexpectedEof,
                         "no lzw end code found",