修复processJoins解析表出现越界.

https://github.com/baomidou/mybatis-plus/issues/6455

mybatis-plus-jsqlparser-support/mybatis-plus-jsqlparser-4.9/src/main/java/com/baomidou/mybatisplus/extension/plugins/inner/BaseMultiTableInnerInterceptor.java

@@ -304,7 +304,7 @@ public abstract class BaseMultiTableInnerInterceptor extends JsqlParserSupport i
                 joinTables = processSubJoin((ParenthesedFromItem) joinItem, whereSegment);
             }
 
-            if (joinTables != null) {
+            if (joinTables != null && !joinTables.isEmpty()) {
 
                 // 如果是隐式内连接
                 if (join.isSimple()) {

mybatis-plus-jsqlparser-support/mybatis-plus-jsqlparser-5.0/src/main/java/com/baomidou/mybatisplus/extension/plugins/inner/BaseMultiTableInnerInterceptor.java

@@ -305,7 +305,7 @@ public abstract class BaseMultiTableInnerInterceptor extends JsqlParserSupport i
                 joinTables = processSubJoin((ParenthesedFromItem) joinItem, whereSegment);
             }
 
-            if (joinTables != null) {
+            if (joinTables != null && !joinTables.isEmpty()) {
 
                 // 如果是隐式内连接
                 if (join.isSimple()) {

mybatis-plus-jsqlparser-support/mybatis-plus-jsqlparser/src/main/java/com/baomidou/mybatisplus/extension/plugins/inner/BaseMultiTableInnerInterceptor.java

@@ -305,7 +305,7 @@ public abstract class BaseMultiTableInnerInterceptor extends JsqlParserSupport i
                 joinTables = processSubJoin((ParenthesedFromItem) joinItem, whereSegment);
             }
 
-            if (joinTables != null) {
+            if (joinTables != null && !joinTables.isEmpty()) {
 
                 // 如果是隐式内连接
                 if (join.isSimple()) {