cannot add a NOT NULL column with default value NULL

app/src/main/java/io/legado/app/data/DatabaseMigrations.kt

@@ -300,7 +300,7 @@ object DatabaseMigrations {
 
     private val migration_37_38 = object : Migration(37, 38) {
         override fun migrate(database: SupportSQLiteDatabase) {
-            database.execSQL("ALTER TABLE book_sources ADD respondTime INTEGER NOT NULL")
+            database.execSQL("ALTER TABLE `book_sources` ADD `respondTime` INTEGER")
         }
     }
 }

app/src/main/java/io/legado/app/data/entities/BookSource.kt

@@ -33,7 +33,7 @@ data class BookSource(
     var loginCheckJs: String? = null,               //登录检测js
     var bookSourceComment: String? = null,          // 注释
     var lastUpdateTime: Long = 0,                   // 最后更新时间，用于排序
-    var respondTime: Long = 180000L,         // 响应时间，用于排序
+    var respondTime: Long? = 180000L,         // 响应时间，用于排序
     var weight: Int = 0,                            // 智能排序的权重
     var exploreUrl: String? = null,                 // 发现url
     var ruleExplore: ExploreRule? = null,           // 发现规则

app/src/main/java/io/legado/app/help/BookSourceAnalyzer.kt

@@ -161,7 +161,7 @@ object BookSourceAnalyzer {
         var loginCheckJs: String? = null,               //登录检测js
         var bookSourceComment: String? = "",             //书源注释
         var lastUpdateTime: Long = 0,                   // 最后更新时间，用于排序
-        var respondTime: Long = 180000L,         // 响应时间，用于排序
+        var respondTime: Long? = 180000L,         // 响应时间，用于排序
         var weight: Int = 0,                            // 智能排序的权重
         var exploreUrl: String? = null,                 // 发现url
         var ruleExplore: Any? = null,           // 发现规则