extract get_signature() for working sets analogous to the same function on the engine state

crates/nu-parser/src/parser.rs

@@ -954,12 +954,7 @@ pub fn parse_internal_call(
     let _ = working_set.add_span(call.head);
 
     let decl = working_set.get_decl(decl_id);
-    let signature = if let Some(block_id) = decl.block_id() {
+    let signature = working_set.get_signature(decl);
-        let block = working_set.get_block(block_id);
-        *block.signature.clone()
-    } else {
-        decl.signature()
-    };
     let output = signature.get_output_type();
 
     // storing the var ID for later due to borrowing issues

crates/nu-protocol/src/engine/state_working_set.rs

@@ -5,7 +5,7 @@ use crate::{
         StateDelta, Variable, VirtualPath, Visibility,
     },
     BlockId, Category, CompileError, Config, DeclId, FileId, GetSpan, Module, ModuleId, ParseError,
-    ParseWarning, Span, SpanId, Type, Value, VarId, VirtualPathId,
+    ParseWarning, Signature, Span, SpanId, Type, Value, VarId, VirtualPathId,
 };
 use core::panic;
 use std::{
@@ -708,6 +708,14 @@ impl<'a> StateWorkingSet<'a> {
         }
     }
 
+    pub fn get_signature(&self, decl: &dyn Command) -> Signature {
+        if let Some(block_id) = decl.block_id() {
+            *self.get_block(block_id).signature.clone()
+        } else {
+            decl.signature()
+        }
+    }
+
     pub fn find_commands_by_predicate(
         &self,
         predicate: impl Fn(&[u8]) -> bool,