update messages and fix coverity issues

Author: alandekok

src/lib/unlang/xlat_expr.c

@@ -3298,6 +3298,11 @@ fr_slen_t xlat_tokenize_expression(TALLOC_CTX *ctx, xlat_exp_head_t **out, fr_sb
 	slen = xlat_tokenize_expression_internal(ctx, out, in, p_rules, t_rules, false);
 	if (slen < 0) return slen;
 
+	if (!*out) {
+		fr_strerror_const("Empty expressions are invalid");
+		return -1;
+	}
+
 	if (xlat_finalize(*out, t_rules->xlat.runtime_el) < 0) {
 		TALLOC_FREE(*out);
 		return -1;
@@ -3314,6 +3319,11 @@ fr_slen_t xlat_tokenize_condition(TALLOC_CTX *ctx, xlat_exp_head_t **out, fr_sbu
 	slen = xlat_tokenize_expression_internal(ctx, out, in, p_rules, t_rules, true);
 	if (slen < 0) return slen;
 
+	if (!*out) {
+		fr_strerror_const("Empty conditions are invalid");
+		return -1;
+	}
+
 	if (xlat_finalize(*out, t_rules->xlat.runtime_el) < 0) {
 		TALLOC_FREE(*out);
 		return -1;

src/lib/unlang/xlat_tokenize.c

@@ -751,7 +751,7 @@ static CC_HINT(nonnull(1,2)) int xlat_tokenize_expansion(xlat_exp_head_t *head,
 		switch (hint) {
 		case '}':
 		empty_disallowed:
-			fr_strerror_const("Empty expression is invalid");
+			fr_strerror_const("Empty expressions are invalid");
 			return -1;
 
 		case '[':

src/tests/unit/xlat/alternation.txt

@@ -39,10 +39,10 @@ xlat %{ || %{User-Name}}
 match ERROR offset 4: Zero length attribute name: Unresolved attributes are not allowed here
 
 xlat %{%{} || }
-match ERROR offset 5: Empty expression is invalid
+match ERROR offset 5: Empty expressions are invalid
 
 xlat %{%{} || foo}
-match ERROR offset 5: Empty expression is invalid
+match ERROR offset 5: Empty expressions are invalid
 
 xlat %{%{User-Name} || 
 match ERROR offset 19: Empty attribute reference

src/tests/unit/xlat/base.txt

@@ -158,7 +158,7 @@ xlat %{
 match ERROR offset 3: Missing closing brace
 
 xlat %{}
-match ERROR offset 3: Empty expression is invalid
+match ERROR offset 3: Empty expressions are invalid
 
 xlat %{:}
 match ERROR offset 3: Zero length attribute name: Unresolved attributes are not allowed here