Fix row number -1 is out of range 0..-1 (#113)

Co-authored-by: hfhbd <[email protected]>

Author: hfhbd

postgres-native-sqldelight-driver/src/commonMain/kotlin/app/softwork/sqldelight/postgresdriver/PostgresNativeDriver.kt

@@ -166,8 +166,9 @@ public class PostgresNativeDriver(
             executeQuery(null, "SELECT name FROM pg_prepared_statements WHERE name = $1", parameters = 1, binders = {
                 bindString(0, identifier.toString())
             }, mapper = {
-                it.next()
-                it.getString(0)
+                if (it.next()) {
+                    it.getString(0)
+                } else null
             })
         return result.value != null
     }