If else not working in ER

a!localVariables(
  local!fabdetails2,local!result,local!samdata,local!samemails,
  local!reassigndetail: a!queryEntity(
    It can return 0 items or result like 
    {{Email: "abc@gmail.com", accid: 10},
    {Email: "xyz@gmail.com", accid: 8}, 
    {Email: "shikhar.gupta@lamresearch.com",accid: 9}}
    This is List of Dictionary - 3 items
  ),

  
  local!fabdetails:
  a!forEach(
    items:local!reassigndetail,
    expression:rule!someexpressionrule(fv!item.accid)
    
    This expression rule returns data as {name:"Jenny",category:"HRA",Region:"USA"}
    so its in loop and it will return  3 records like 
    List of Variant
      > List of Dictionary
        > Dictionary
     > List of Dictionary
        > Dictionary 
     > List of Dictionary
        > Dictionary 

  ),
  
  
 if(length(local!reassigndetail)<1,
  null,
  local!fabdetails2: a!forEach(a!flatten( local!fabdetails).name,fv!item),
  local!samemails: a!forEach(a!flatten( local!reassigndetail).Email,fv!item)
  ,


  local!samdata : a!queryEntity(
    entity: cons!MPPCONSCDT_SAMAccountability,
    query: a!query(
      logicalExpression: a!queryLogicalExpression(
        operator: "AND",
        filters: {
          a!queryFilter(
            field: "email",
            operator: "in",
            value:local!samemails
          ),
          a!queryFilter(
            field: "name",
            operator: "in",
            value:local!fabdetails2
          )
        },
        ignoreFiltersWithEmptyValues: true
      ),
      pagingInfo: a!pagingInfo(
        startIndex: 1,
        batchSize: 50
      )
    ),
    fetchTotalCount: false
  ).data,

  local!result:
  a!forEach(
    items:local!samdata,
    expression: cast(typeof('type!{urn:com:appian:types}MPPSAMAccoumtability'()),fv!item)
  ),
  local!result
  
  )
  
)

Its giving error with if else

help me to fix

a!localVariables(
  local!reassigndetail: a!queryEntity(
    It can return 0 items or result like 
    {{Email: "abc@gmail.com", accid: 10},
    {Email: "xyz@gmail.com", accid: 8}, 
    {Email: "shikhar.gupta@lamresearch.com",accid: 9}}
    This is List of Dictionary - 3 items
  ),

  
  local!fabdetails:
  a!forEach(
    items:local!reassigndetail,
    expression:rule!someexpressionrule(fv!item.accid)
    
    This expression rule returns data as {name:"Jenny",category:"HRA",Region:"USA"}
    so its in loop and it will return  3 records like 
    List of Variant
      > List of Dictionary
        > Dictionary
     > List of Dictionary
        > Dictionary 
     > List of Dictionary
        > Dictionary 

  ),
  
  

  local!fabdetails2: a!forEach(a!flatten( local!fabdetails).name,fv!item),
  local!samemails: a!forEach(a!flatten( local!reassigndetail).Email,fv!item)
  ,


  local!samdata : a!queryEntity(
    entity: cons!MPPCONSCDT_SAMAccountability,
    query: a!query(
      logicalExpression: a!queryLogicalExpression(
        operator: "AND",
        filters: {
          a!queryFilter(
            field: "email",
            operator: "in",
            value:local!samemails
          ),
          a!queryFilter(
            field: "name",
            operator: "in",
            value:local!fabdetails2
          )
        },
        ignoreFiltersWithEmptyValues: true
      ),
      pagingInfo: a!pagingInfo(
        startIndex: 1,
        batchSize: 50
      )
    ),
    fetchTotalCount: false
  ).data,

  local!result:
  a!forEach(
    items:local!samdata,
    expression: cast(typeof('type!{urn:com:appian:types}MPPSAMAccoumtability'()),fv!item)
  ),
  local!result
  
  
)

If I remove if else, then it works fine if local!reassign fab have some data , if empty it gives error