fix: EXPOSED-580 MigrationsUtils.statementsRequiredForDatabaseMigration throws an error when a table is passed that does not already exist in the database

The problem was in the `existingIndices` function. For some dialects, querying indices for a table that does not exist throws an error. This is fixed in the `existingIndices` function by filtering the tables and using only those that exist.

Author: joc-a

exposed-core/src/main/kotlin/org/jetbrains/exposed/sql/vendors/VendorDialect.kt

@@ -115,7 +115,7 @@ abstract class VendorDialect(
     }
 
     override fun existingIndices(vararg tables: Table): Map<Table, List<Index>> =
-        TransactionManager.current().db.metadata { existingIndices(*tables) }
+        TransactionManager.current().db.metadata { existingIndices(tables = tables.filter { it.exists() }.toTypedArray()) }
 
     override fun existingPrimaryKeys(vararg tables: Table): Map<Table, PrimaryKeyMetadata?> =
         TransactionManager.current().db.metadata { existingPrimaryKeys(*tables) }

exposed-tests/src/test/kotlin/org/jetbrains/exposed/sql/tests/shared/ddl/DatabaseMigrationTests.kt

@@ -133,6 +133,23 @@ class DatabaseMigrationTests : DatabaseTestsBase() {
         }
     }
 
+    @Test
+    fun testCreateStatementsGeneratedForTablesThatDoNotExist() {
+        val tester = object : Table("tester") {
+            val bar = char("bar")
+        }
+
+        withDb {
+            val statements = MigrationUtils.statementsRequiredForDatabaseMigration(tester, withLogs = false)
+            assertEquals(1, statements.size)
+            assertEquals(
+                "CREATE TABLE${" IF NOT EXISTS".takeIf { currentDialectTest.supportsIfNotExists } ?: ""} ${tester.nameInDatabaseCase()} " +
+                    "(${"bar".inProperCase()} CHAR NOT NULL)",
+                statements.first()
+            )
+        }
+    }
+
     @Test
     fun testDropUnmappedColumnsStatementsIdentical() {
         val t1 = object : Table("foo") {