fix: panic of if command as a constant expr by bringing back Type::Block (#16122)

Fixes #16110. Alternative to #16120 

# Description

# User-Facing Changes

no more panic

# Tests + Formatting

+1

# After Submitting

crates/nu-parser/src/parse_keywords.rs

@@ -2487,7 +2487,7 @@ pub fn parse_module(
         working_set,
         Expr::Block(block_id),
         block_expr_span,
-        Type::Any,
+        Type::Block,
     );
 
     let module_decl_id = working_set

crates/nu-parser/src/parser.rs

@@ -4768,7 +4768,7 @@ pub fn parse_block_expression(working_set: &mut StateWorkingSet, span: Span) ->
 
     let block_id = working_set.add_block(Arc::new(output));
 
-    Expression::new(working_set, Expr::Block(block_id), span, Type::Any)
+    Expression::new(working_set, Expr::Block(block_id), span, Type::Block)
 }
 
 pub fn parse_match_block_expression(working_set: &mut StateWorkingSet, span: Span) -> Expression {

crates/nu-parser/src/type_check.rs

@@ -88,6 +88,7 @@ pub fn type_compatible(lhs: &Type, rhs: &Type) -> bool {
         (Type::Int, Type::Number) => true,
         (Type::Number, Type::Float) => true,
         (Type::Float, Type::Number) => true,
+        (Type::Closure, Type::Block) => true,
         (Type::Any, _) => true,
         (_, Type::Any) => true,
         (Type::Record(lhs), Type::Record(rhs)) | (Type::Table(lhs), Type::Table(rhs)) => {