Bubble up errors passed to complete (#11313)

Errors passed in `PipelineData::Value` get thrown in `complete` now.

Also added two simple tests for the command.

Fix #11187
Fix #10204

crates/nu-command/tests/commands/mod.rs

@@ -7,6 +7,7 @@ mod break_;
 mod cal;
 mod cd;
 mod compact;
+mod complete;
 mod config_env_default;
 mod config_nu_default;
 mod continue_;