Fix polymorphic record "too few" lacking error message

src/check_expr.cpp

@@ -5286,8 +5286,8 @@ CallArgumentError check_polymorphic_record_type(CheckerContext *c, Operand *oper
 	TypeTuple *tuple = get_record_polymorphic_params(original_type);
 	isize param_count = tuple->variables.count;
 	isize minimum_param_count = param_count;
-	for (minimum_param_count = tuple->variables.count-1; minimum_param_count >= 0; minimum_param_count--) {
+	for (; minimum_param_count > 0; minimum_param_count--) {
-		Entity *e = tuple->variables[minimum_param_count];
+		Entity *e = tuple->variables[minimum_param_count-1];
 		if (e->kind != Entity_Constant) {
 			break;
 		}
@@ -5296,6 +5296,7 @@ CallArgumentError check_polymorphic_record_type(CheckerContext *c, Operand *oper
 		}
 	}
 
+
 	Array<Operand> ordered_operands = operands;
 	if (!named_fields) {
 		ordered_operands = array_make<Operand>(permanent_allocator(), param_count);
@@ -5367,6 +5368,13 @@ CallArgumentError check_polymorphic_record_type(CheckerContext *c, Operand *oper
 		return err;
 	}
 
+	while (ordered_operands.count >= 0) {
+		if (ordered_operands[ordered_operands.count-1].expr != nullptr) {
+			break;
+		}
+		array_pop(&ordered_operands);
+	}
+
 	if (minimum_param_count != param_count) {
 		if (param_count < ordered_operands.count) {
 			error(call, "Too many polymorphic type arguments, expected a maximum of %td, got %td", param_count, ordered_operands.count);

src/check_type.cpp

@@ -250,9 +250,14 @@ Entity *find_polymorphic_record_entity(CheckerContext *ctx, Type *original_type,
 
 			bool skip = false;
 
+			GB_ASSERT(ordered_operands.count >= param_count);
+
 			for (isize j = 0; j < param_count; j++) {
 				Entity *p = tuple->variables[j];
 				Operand o = ordered_operands[j];
+				if (o.expr == nullptr) {
+					return nullptr;
+				}
 				Entity *oe = entity_of_node(o.expr);
 				if (p == oe) {
 					// NOTE(bill): This is the same type, make sure that it will be be same thing and use that

src/checker.cpp

@@ -937,7 +937,7 @@ Type *type_of_expr(Ast *expr) {
 }
 
 Entity *implicit_entity_of_node(Ast *clause) {
-	if (clause->kind == Ast_CaseClause) {
+	if (clause != nullptr && clause->kind == Ast_CaseClause) {
 		return clause->CaseClause.implicit_entity;
 	}
 	return nullptr;