Adds missing return, updates test case

Author: MasonRemaley

src/Sema/LowerZon.zig

@@ -104,7 +104,7 @@ fn lowerExprAnonResTy(self: *LowerZon, node: Zoir.Node.Index) CompileError!Inter
             const result = try self.sema.addStrLit(ip_str, val.len);
             return result.toInterned().?;
         },
-        .empty_literal => .empty_tuple,
+        .empty_literal => return .empty_tuple,
         .array_literal => |nodes| {
             const types = try self.sema.arena.alloc(InternPool.Index, nodes.len);
             const values = try self.sema.arena.alloc(InternPool.Index, nodes.len);

test/cases/compile_errors/@import_zon_anon_nan.zig

@@ -5,5 +5,5 @@ export fn entry() void {
 // error
 // imports=zon/nan.zon
 //
-// nan.zon:1:1: error: nan requires a known result type
+// nan.zon:1:1: error: NaN requires a known result type
 // tmp.zig:2:17: note: imported here