fix: guard against corrupt __dbis__ entries crashing startup

Null-check decoded values from attributesDbi.getRange() in both
initStores and the table() function — RecordEncoder.decode returns null
on error (e.g. mismatched structon typedStructs after a version
mismatch), and the subsequent property accesses (value.name,
value.isPrimaryKey) would throw.  Corrupt entries are now silently
skipped; RecordEncoder already logs the decode error.

Also guard databases.system before the 'in' check in
checkIfInstallIsSupported: if getDatabases() throws mid-scan,
loadedDatabases is already true but databases.system is never
populated, producing a TypeError on the next startup.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: kriszyp

dataLayer/hdbInfoController.ts

@@ -237,7 +237,7 @@ function checkIfInstallIsSupported(dataVNum) {
 		'In order to upgrade to this version, you must do a fresh install. If you need support, ' +
 		`please contact ${hdbTerms.HDB_SUPPORT_ADDRESS}`;
 
-	if (!('hdb_info' in tableLoader.databases.system)) {
+	if (!tableLoader.databases.system || !('hdb_info' in tableLoader.databases.system)) {
 		console.log(errMsg);
 		throw new Error(errMsg);
 	}

resources/databases.ts

@@ -506,6 +506,7 @@ function initStores(
 
 	for (const result of attributesDbi.getRange({ start: false })) {
 		const { key, value } = result as { key: string; value: any };
+		if (value == null) continue;
 		let [tableName, attribute_name] = key.toString().split('/');
 		if (attribute_name === '') {
 			// primary key
@@ -1104,6 +1105,7 @@ export function table<TableResourceType>(tableDefinition: TableDefinition): Tabl
 	Table.dbisDB = attributesDbi;
 	const indicesToRemove = [];
 	for (const { key, value } of attributesDbi.getRange({ start: true })) {
+		if (value == null) continue;
 		let [attributeTableName, attribute_name] = key.toString().split('/');
 		if (attribute_name === '') attribute_name = value.name; // primary key
 		if (attribute_name) {