Hi ,
I am getting issue in catch block due to retrun statement .Can anyone help me in this
Main Class

public with sharing class Common_DAO 
{
    //get the list of Table Component records
    public static List<Common_TableComponent__c> getTableComponentList(string recordName)
    {
        try
        {
            List<Common_TableComponent__c> tempList = new List<Common_TableComponent__c>();
            
            tempList = [SELECT ActionButtons__c,Advanced_Search_Criteria__c,Advanced_Search_Help_Text__c,
                        ColumnHeaderList__c,Columns_To_Sort__c,
                        Date_Filter_Values_New__c,DefaultView__c,Default_Filter_Column__c,Enable_Advanced_Search__c,Enable_Date_Filter__c,
                        Enable_Search__c,Enable_Sorting__c,Fields__c,IsActionColumnEnabled__c,Order_By_Clause__c,
                        Pagination_Type__c,SearchFields__c,Search_Help_Text__c,SOQLQuery__c,Where_Clause__c, Header_Default_Value__c,Header_Spanish_Value__c 
                        FROM Common_TableComponent__c WHERE Name = :recordName LIMIT 1];
            
            return tempList;
        }
        catch(exception e)
        {
            return null;
        }
    }
    
    //get the list of Table Search records
    public static List<Common_TableSearch__c> getTableSearchList(string recordName, string searchType)
    {
        try
        {
            List<Common_TableSearch__c> tempList = new List<Common_TableSearch__c>();
            
            tempList = [SELECT Name, Advanced_Search_SOQL_Query__c, Common_TableComponent__c,
                        Field_Type__c, Join_Column__c, Placeholder_Text__c, Possible_Values__c,
                        Search_Type__c,  Child_Column__c,Default_Filter_Column__c,Where__c,Order_By__c,Default_Filter_Value_SOQL__c,Default_Filter_Child_Column__c  
                        from Common_TableSearch__c 
                        where Common_TableComponent__r.Name = :recordName and Search_Type__c=: searchType order by Sequence_Number__c ];
            
            return tempList;
        }
        catch(exception e)
        {
            return null;
        }
    }
    
    //get the list of Table Search records
    public static List<Common_TableAction__c> getTableActionList(set<string> buttonsNameSet)
    {
        try
        {
            List<Common_TableAction__c> tempList = new List<Common_TableAction__c>();
            
            tempList = [SELECT Name,Action_Button_Display_Column_Values__c,
                        Action_Button_Display_Criteria_Column__c,
                        Action_Button_Ext_Display_Column_Values__c,
                        Action_Button_External_Display_Criteria__c,
                        APINameOfLink__c,Custom_Permissions__c,DynamicParams__c,
                        EnableAsLink__c,Is_Absolute_URL__c,IsActive__c,
                        Is_Remote_Action_Button__c,Enable_Pop_up__c,Self_Window__c,
                        Remote_Action_Class__c,Remote_Action_Method__c,Title__c,URL__c 
                        FROM Common_TableAction__c where Name IN : buttonsNameSet];
            
            return tempList;
        }
        catch(exception e)
        {
            return null;
        }
    }
}

Test class 
@IsTest
Public class Common_DAO_Test{
     @isTest  static testmethod void common_DAOTest1(){
     
        string recordName='';
        string searchType='';
        set<string> buttonsNameSet=new set<string> ();
        Common_DAO c=new Common_DAO();
        Common_DAO.getTableComponentList(recordName);
        Common_DAO.getTableSearchList(recordName,searchType);
        Common_DAO.getTableActionList(buttonsNameSet);
        system.assertequals(searchType,'');    
    }
    
    Public static testmethod void common_DAOTest2(){
        Common_DAO c=new Common_DAO();
        string recordName='test';
        string searchType='test';
        set<string> buttonsNameSet=new set<string> {'test'};
            
            
            try{
            
            Common_DAO.getTableComponentList(recordName);
           
            } catch(DMLException e) {
            
            system.assertEquals(e.getMessage(), e.getMessage()); 
            
            } 
            Common_DAO.getTableSearchList(recordName,searchType);
            Common_DAO.getTableActionList(buttonsNameSet);
        }