Fix error message not propagating in decompressors

Author: Col-E

src/main/java/software/coley/lljzip/format/compression/DeflateDecompressor.java

@@ -50,7 +50,7 @@ public ByteData decompress(LocalFileHeader header, ByteData data) throws IOExcep
 			} while (!inflater.finished());
 		} catch (DataFormatException e) {
 			String s = e.getMessage();
-			throw (ZipException) new ZipException(s != null ? null : "Invalid ZLIB data format").initCause(e);
+			throw (ZipException) new ZipException(s != null ? s : "Invalid ZLIB data format").initCause(e);
 		} finally {
 			inflater.end();
 		}

src/main/java/software/coley/lljzip/format/compression/UnsafeDeflateDecompressor.java

@@ -90,7 +90,7 @@ public ByteData decompress(LocalFileHeader header, ByteData data) throws IOExcep
 			} while (true);
 		} catch (DataFormatException e) {
 			String s = e.getMessage();
-			throw (ZipException) new ZipException(s != null ? null : "Invalid ZLIB data format").initCause(e);
+			throw (ZipException) new ZipException(s != null ? s : "Invalid ZLIB data format").initCause(e);
 		} finally {
 			end:
 			{