powershell method on a null-valued expression - powershell

Question

I have a script thats been running fine for months but over the last few days when I run it I'm getting this error - any help in debugging it?
here's line 66 in the code:
$remotefilehash = ($remoteFiles | Where-Object { -not ($_ | Select-String -Quiet -NotMatch -Pattern '^[a-f0-9]{32}( )') } -replace '^[a-f0-9]{32}( )', '$0= ' -join "`n") | ConvertFrom-StringData
I wonder if for some reason $remoteFiles is zero ? ie null and hence throws this error?
Where-Object : A parameter cannot be found that matches parameter name 'replace'.
At P:\scripts\code\pcloud_sync.ps1:66 char:125
+ ... ing -Quiet -NotMatch -Pattern '^[a-f0-9]{32}( )') } -replace '^[a-f0 ...
+ ~~~~~~~~
+ CategoryInfo : InvalidArgument: (:) [Where-Object], ParameterBindingException
+ FullyQualifiedErrorId : NamedParameterNotFound,Microsoft.PowerShell.Commands.WhereObjectCommand
You cannot call a method on a null-valued expression.
At P:\scripts\code\pcloud_sync.ps1:74 char:1
+ $diffmd5 = $remotefilehash.GetEnumerator().Where({ -not $localHashSet ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : InvalidOperation: (:) [], RuntimeException
+ FullyQualifiedErrorId : InvokeMethodOnNull
UPDATE2
after adding the parthensis now getting another new error on the same line:
ConvertFrom-StringData : Data item 'a3512c98c9e159c021ebbb76b238707e' in line 'a3512c98c9e159c021ebbb76b238707e = My
Pictures/Tony/Automatic Upload/Tony’s iPhone/2022-10-08 21-46-21 (2).mov' is already defined.
At P:\scripts\code\pcloud_sync.ps1:66 char:179
+ ... ace '^[a-f0-9]{32}( )', '$0= ' -join "`n") | ConvertFrom-StringData
+ ~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : InvalidOperation: (:) [ConvertFrom-StringData], PSInvalidOperationException
+ FullyQualifiedErrorId : InvalidOperation,Microsoft.PowerShell.Commands.ConvertFromStringDataCommand
You cannot call a method on a null-valued expression.
At P:\scripts\code\pcloud_sync.ps1:74 char:1
+ $diffmd5 = $remotefilehash.GetEnumerator().Where({ -not $localHashSet ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : InvalidOperation: (:) [], RuntimeException
+ FullyQualifiedErrorId : InvokeMethodOnNull