Clean up errors for invalid commands and add regression tests.

* src/function.c (func_shell_base): Use error() instead of recreating
the error output.
* src/job.c (exec_command): Show more standard error messages.
* src/load.c (unload_file): Fix whitespace in the error message.
* tests/scripts/features/errors: Add tests for starting non-
existent commands and new error message formats.
* tests/scripts/features/output-sync: New error message formats.
* tests/scripts/functions/shell: Ditto.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/load.c b/src/load.c
index ecf66cba..5ec87c6b 100644
--- a/src/load.c
+++ b/src/load.c
@@ -240,7 +240,7 @@ unload_file (const char *name)
     if (streq (d->name, name) && d->dlp)
       {
         if (dlclose (d->dlp))
-          perror_with_name ("dlclose", d->name);
+          perror_with_name ("dlclose: ", d->name);
         d->dlp = NULL;
         break;
       }