Symbol finder gives error message

[ghost]

Description

What steps will reproduce the problem?

1. Move the Spyder config folder that you have a clean start.
2. Open "Symbol finder" (Ctrl+Alt+P)
3. "Symbol finder" opens.
4. Click somewhere else than the "Symbol finder window".
5. The error message below pops up.

What is the expected output? What do you see instead?
Ooening and closing the "Symbol finder window" by clicking somewhere else should close the "Symbol finder window" just normally, instead a error windows pops up.

Please provide any additional information below

File "~/SpyderBug/spyder/spyder/widgets/fileswitcher.py", line 397, in restore_initial_state
for path in self.initial_cursors:
TypeError: 'NoneType' object is not iterable

Version and main components

• Spyder Version: 4.0.0.dev0 5083a69
• Python Version: 3.6.2
• Qt Versions: 5.7.1, PyQt5 5.8.1 on Linux

Dependencies

pyflakes >=0.6.0 :  1.5.0 (OK)
pycodestyle >=2.3:  2.3.1 (OK)
pygments >=2.0   :  2.2.0 (OK)
pandas >=0.13.1  :  None (NOK)
numpy >=1.7      :  1.12.1 (OK)
sphinx >=0.6.6   :  1.5.2 (OK)
rope >=0.9.4     :  None (NOK)
jedi >=0.9.0     :  0.10.2 (OK)
psutil >=0.3     :  5.0.1 (OK)
nbconvert >=4.0  :  4.2.0 (OK)
sympy >=0.7.3    :  1.1.1 (OK)
cython >=0.21    :  None (NOK)
qtconsole >=4.2.0:  4.2.1 (OK)
IPython >=4.0    :  5.3.0 (OK)
pylint >=0.25    :  1.7.4 (OK)

[ccordoba12]

@dalthviz, I think this error was introduced by you. Please take a look at it.