Uninstall-ChocolateyPackage is treating UninstallString like a file path

[AnthonyMastrean]

PS> Get-UninstallRegistryKey -SoftwareName 'Smallpdf'

DisplayIcon          : C:\Users\anthony.mastrean\AppData\Local\Smallpdf\app.ico
DisplayName          : Smallpdf
DisplayVersion       : 1.11.0
InstallDate          : 20180607
InstallLocation      : C:\Users\anthony.mastrean\AppData\Local\Smallpdf
Publisher            : Smallpdf
QuietUninstallString : "C:\Users\anthony.mastrean\AppData\Local\Smallpdf\Update.exe" --uninstall -s
UninstallString      : "C:\Users\anthony.mastrean\AppData\Local\Smallpdf\Update.exe" --uninstall
URLUpdateInfo        :
EstimatedSize        : 105739
NoModify             : 1
NoRepair             : 1
Language             : 1033
PSPath               : Microsoft.PowerShell.Core\Registry::HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Uninstall\Smallpdf
PSParentPath         : Microsoft.PowerShell.Core\Registry::HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Uninstall
PSChildName          : Smallpdf
PSProvider           : Microsoft.PowerShell.Core\Registry

anthony.mastrean@VAE-LT1131 ~\Projects\github.com\AnthonyMastrean\chocolateypackages [master ≡ +1 ~0 -0 !]
PS> choco uninstall -fy smallpdf
Chocolatey v0.10.7
Uninstalling the following packages:
smallpdf

smallpdf v1.11.0 (forced)
Uninstalling smallpdf...
ERROR: Exception calling "GetFullPath" with "1" argument(s): "Illegal characters in path."
smallpdf uninstall not successful.
Error while running 'C:\ProgramData\chocolatey\lib\smallpdf\tools\chocolateyuninstall.ps1'.
 See log for details.
smallpdf not uninstalled. An error occurred during uninstall:
 smallpdf uninstall not successful.

Chocolatey uninstalled 0/1 packages. 1 packages failed.
 See the log for details (C:\ProgramData\chocolatey\logs\chocolatey.log).

Failures
 - smallpdf (exited -1) - Error while running 'C:\ProgramData\chocolatey\lib\smallpdf\tools\chocolateyuninstall.ps1'.
 See log for details.

If a package uninstall is failing and/or you've already uninstalled the
 software outside of Chocolatey, you can attempt to run the command
 with `-n` to skip running a chocolateyUninstall script, additionally
 adding `--skip-autouninstaller` to skip an attempt to automatically
 remove system-installed software. This will only remove the packaging
 files and not things like software installed to Programs and Features.

If a package is failing because it is a dependency of another package
 or packages, then you may first need to consider if it needs removed
 as it is typically installed as a dependency for a reason. If you
 decide that you still want to remove it, head into
 `$env:ChocolateyInstall\lib` and find the package folder you want
 removed. Then delete the folder for the package. This option should
 only be used as a last resort.