patch 8.2.2137: Vim9: :echo and :execute give error for empty argument

Problem:    Vim9: :echo and :execute give error for empty argument.
Solution:   Ignore an empty argument. (closes #7468)
diff --git a/src/errors.h b/src/errors.h
index 30f0dc5..b8cb32f 100644
--- a/src/errors.h
+++ b/src/errors.h
@@ -61,7 +61,7 @@
 	INIT(= N_("E1013: Argument %d: type mismatch, expected %s but got %s"));
 EXTERN char e_invalid_key_str[]
 	INIT(= N_("E1014: Invalid key: %s"));
-EXTERN char e_name_expected[]
+EXTERN char e_name_expected_str[]
 	INIT(= N_("E1015: Name expected: %s"));
 EXTERN char e_cannot_declare_a_scope_variable[]
 	INIT(= N_("E1016: Cannot declare a %s variable: %s"));
@@ -315,3 +315,5 @@
 	INIT(= N_("E1141: Indexable type required"));
 EXTERN char e_non_empty_string_required[]
 	INIT(= N_("E1142: Non-empty string required"));
+EXTERN char e_empty_expression_str[]
+	INIT(= N_("E1143: empty expression: \"%s\""));