input/InputStream: migrate from class Error to C++ exceptions

src/TagFile.cxx

@@ -68,8 +68,12 @@ public:
 			} catch (const std::runtime_error &) {
 				return false;
 			}
-		} else
-			is->LockRewind(IgnoreError());
+		} else {
+			try {
+				is->LockRewind();
+			} catch (const std::runtime_error &) {
+			}
+		}
 
 		/* now try the stream_tag() method */
 		return plugin.ScanStream(*is, handler, handler_ctx);