Add nullptr assert for odin-lang#5875

Author: Kelimion

src/check_type.cpp

@@ -1633,6 +1633,8 @@ gb_internal bool is_expr_from_a_parameter(CheckerContext *ctx, Ast *expr) {
 	} else if (expr->kind == Ast_Ident) {
 		Operand x= {};
 		Entity *e = check_ident(ctx, &x, expr, nullptr, nullptr, true);
+		GB_ASSERT(e != nullptr);
+
 		if (e->flags & EntityFlag_Param) {
 			return true;
 		}