`TypeError: can only concatenate str (not "type") to str` instead of actual error
### Issue description

In some cases, `pipenv` outputs `TypeError: can only concatenate str (not "type") to str` instead of the actual error (or after printing out the actual error). It faces an error while handling the actual error.

### Steps to replicate

Set WORKON_HOME to somewhere that current user doesn't have permission for writing to. Example:

`WORKON_HOME=/opt/  pipenv install`

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I encountered the issue on the latest source code from the Github.
diff --git a/pipenv/vendor/delegator.py b/pipenv/vendor/delegator.py
index cf6f91c8..367f52b0 100644
--- a/pipenv/vendor/delegator.py
+++ b/pipenv/vendor/delegator.py
@@ -112,7 +112,7 @@ class Command(object):
         if self.subprocess.before:
             result += self.subprocess.before
 
-        if self.subprocess.after and self.subprocess.after is not pexpect.EOF:
+        if self.subprocess.after and self.subprocess.after not in (pexpect.EOF, pexpect.TIMEOUT):
             try:
                 result += self.subprocess.after
             except (pexpect.EOF, pexpect.TIMEOUT):
['pipenv/vendor/delegator.py']