Write upgrade/not-installed notices to stderr

Signed-off-by: Julius Härtl <jus@bitgrid.net>

lib/private/Console/Application.php

@@ -142,12 +142,14 @@ class Application {
 					}
 				}
 			} elseif ($input->getArgument('command') !== '_completion' && $input->getArgument('command') !== 'maintenance:install') {
-				$output->writeln("Nextcloud is not installed - only a limited number of commands are available");
+				$errorOutput = $output->getErrorOutput();
+				$errorOutput->writeln("Nextcloud is not installed - only a limited number of commands are available");
 			}
 		} catch (NeedsUpdateException $e) {
 			if ($input->getArgument('command') !== '_completion') {
-				$output->writeln("Nextcloud or one of the apps require upgrade - only a limited number of commands are available");
-				$output->writeln("You may use your browser or the occ upgrade command to do the upgrade");
+				$errorOutput = $output->getErrorOutput();
+				$errorOutput->writeln("Nextcloud or one of the apps require upgrade - only a limited number of commands are available");
+				$errorOutput->writeln("You may use your browser or the occ upgrade command to do the upgrade");
 			}
 		}