Do not crash on errors.

The SPARQL iterator (source) passes errors to the writer (destination),
but ldf-client only handled errors from the source.
Hence, if something went wrong with the iterator,
the error passed to the writer was not caught.

Author: RubenVerborgh

bin/ldf-client

@@ -66,24 +66,26 @@ try {
   case 'SELECT':
     writer = ldf.SparqlResultWriter.instantiate(mimeType, sparqlIterator);
     writer.on('data', function (data) { process.stdout.write(data); });
+    writer.on('error', reportError);
     break;
   // Write an RDF representation of all results
   case 'CONSTRUCT':
   case 'DESCRIBE':
     config.end = false; // stdout cannot be closed
     writer = new N3.Writer(process.stdout, config);
     sparqlIterator.on('data', function (triple) { writer.addTriple(triple); })
-                  .on('end',  function () { writer.end(); });
+                  .on('end',  function () { writer.end(); })
+                  .on('error', reportError);
     break;
   default:
     throw new ldf.SparqlIterator.UnsupportedQueryError(query);
   }
 
-  // Report an error's stack trace
-  sparqlIterator.on('error', function (error) {
+  // Reports an error's stack trace
+  function reportError(error) {
     console.error('ERROR: An error occurred during query execution.\n');
     console.error(error.stack);
-  });
+  }
 }
 // Report a synchronous error
 catch (error) {