The referred error might happen between line 58 and 86

error.ps1

function Write-Char {
    param(
        [ValidateLength(1,1)]
        [string]$char
    )
    ##############TEMP#################
    $alphabet = @{
        A = 0x3E, 0x05, 0x3E
        B = 0x1F, 0x15, 0x0A
        C = 0x0E, 0x11, 0x11
        D = 0x1F, 0x11, 0x0E
        E = 0x1F, 0x15, 0x11
        F = 0x1F, 0x05, 0x01
        G = 0x0E, 0x11, 0x1D
        H = 0x1F, 0x04, 0x1F
        I = 0x11, 0x1F, 0x11
        J = 0x09, 0x11, 0x0F
        K = 0x1F, 0x04, 0x1B
        L = 0x1F, 0x10, 0x10
        M = 0x1F, 0x02, 0x04, 0x02, 0x1F
        N = 0x1F, 0x02, 0x0C, 0x1F
        O = 0x0E, 0x11, 0x0E
        P = 0x1F, 0x09, 0x06
        Q = 0x0E, 0x11, 0x09, 0x16
        R = 0x1F, 0x09, 0x16
        S = 0x12, 0x15, 0x09
        T = 0x01, 0x1F, 0x01
        U = 0x0F, 0x10, 0x10, 0x0F
        V = 0x0F, 0x10, 0x0F
        W = 0x0F, 0x10, 0x08,0x10,0x0F
        X = 0x1D, 0x04, 0x1D
        Y = 0x03, 0x1C, 0x03
        Z = 0x19, 0x15, 0x13
        "1" = 0x12, 0x1F, 0x10
        "2" = 0x19, 0x15, 0x12
        "3" = 0x11, 0x15, 0x0A
        "4" = 0x0E, 0x09, 0x1C
        "5" = 0x17, 0x15, 0x09
        "6" = 0x0E, 0x15, 0x08
        "7" = 0x19, 0x05, 0x03
        "8" = 0x0A, 0x15, 0x0A
        "9" = 0x02, 0x15, 0x0E
        "0" = 0x0E, 0x15, 0x0E
        "!" = 0x17
        " " = 0X00,0X00
    }
    ###################################
    #get respective bits from hashtable
    $bitsArray = $alphabet[$char] # this is an array with required data
    $totalRegistersRequired = $Script:CurrentRegisterValues.Count + $bitsArray.Count

    $registers = ($Script:CurrentRegisterValues.Count+1) .. $totalRegistersRequired

    if($totalRegistersRequired -gt $Script:TotalRegisters ) # this means that we will need to start shifting
    {
        $i = 0
        $wroteWhiteSpace = $false
        while($i -lt $bitsArray.Count)
        {
            #send the first value out.
            $null, $Script:CurrentRegisterValues = $Script:CurrentRegisterValues

            #SHIFT!
            for($j = 1 ; $j -le 10; ++$j) #10 because we will leave the 11 to the new value
            {
                Set-I2CRegister -Device $Script:Device -Register $j -Data $Script:CurrentRegisterValues[$j-1]
                Update-Registers
            }


            #start by writing a white column
            if($wroteWhiteSpace -eq $false)
            {
                Set-I2CRegister -Device $Script:Device -Register 0xB -Data 0
                $Script:CurrentRegisterValues+= 0
                #Update-Registers
                $wroteWhiteSpace = $true
                continue
            }

            Set-I2CRegister -Device $Script:Device -Register 0xB -Data $bitsArray[$i]
            $Script:CurrentRegisterValues += $bitsArray[$i++]
            Update-Registers
            Start-Sleep -Milliseconds 5
        }
        return
    }
    #if we get here, this is one of the first letters
    $i = 0
    foreach($register in $registers)
    {
        Set-I2CRegister -Device $Script:Device -Register $register -Data $bitsArray[$i]
        $Script:CurrentRegisterValues += $bitsArray[$i++]
    }
}