Fix error reporting when opening pack files

Author: nikitalita

core/io/file_access.cpp

@@ -159,19 +159,24 @@ Error FileAccess::reopen(const String &p_path, int p_mode_flags) {
 Ref<FileAccess> FileAccess::open(const String &p_path, int p_mode_flags, Error *r_error) {
 	//try packed data first
 
+	Error err = OK;
 	Ref<FileAccess> ret;
 	if (!(p_mode_flags & WRITE) && !(p_mode_flags & SKIP_PACK) && PackedData::get_singleton() && !PackedData::get_singleton()->is_disabled()) {
 		ret = PackedData::get_singleton()->try_open_path(p_path);
 		if (ret.is_valid()) {
+			err = ret->get_error();
 			if (r_error) {
-				*r_error = OK;
+				*r_error = err;
+			}
+			if (err != OK) {
+				ret.unref();
 			}
 			return ret;
 		}
 	}
 
 	ret = create_for_path(p_path);
-	Error err = ret->open_internal(p_path, p_mode_flags & ~SKIP_PACK);
+	err = ret->open_internal(p_path, p_mode_flags & ~SKIP_PACK);
 
 	if (r_error) {
 		*r_error = err;

core/io/file_access_pack.cpp

@@ -447,7 +447,11 @@ void FileAccessPack::set_big_endian(bool p_big_endian) {
 }
 
 Error FileAccessPack::get_error() const {
-	if (eof) {
+	if (encryption_error) {
+		return encryption_error;
+	} else if (f.is_null()) {
+		return ERR_FILE_CANT_OPEN;
+	} else if (eof) {
 		return ERR_FILE_EOF;
 	}
 	return OK;
@@ -494,8 +498,8 @@ FileAccessPack::FileAccessPack(const String &p_path, const PackedData::PackedFil
 			key.write[i] = script_encryption_key[i];
 		}
 
-		Error err = fae->open_and_parse(f, key, FileAccessEncrypted::MODE_READ, false);
-		ERR_FAIL_COND_MSG(err, vformat("Can't open encrypted pack-referenced file '%s'.", String(pf.pack)));
+		encryption_error = fae->open_and_parse(f, key, FileAccessEncrypted::MODE_READ, false);
+		ERR_FAIL_COND_MSG(encryption_error, vformat("Can't open encrypted pack-referenced file '%s'.", String(pf.pack)));
 		f = fae;
 		off = 0;
 	}

core/io/file_access_pack.h

@@ -168,6 +168,7 @@ class FileAccessPack : public FileAccess {
 
 	mutable uint64_t pos;
 	mutable bool eof;
+	Error encryption_error = OK;
 	uint64_t off;
 
 	Ref<FileAccess> f;