Getting an error when installing an existing/customized app

Hi,
Please help i recently manually deleted an app by deleting the folder and removing it in apps.txt,
also deleted the site in which it was installed on by removing its folder in the apps folder and its database.
I then created a new site using ‘bench new-site [sitename]’ command, after that fetched the erpnext (already modified) app from a forked repo using the ‘bench get-app [source-link]’ command.
All worked well
But on trying to install the app on the site, after the updating [===] process completed,
I get this error
Traceback (most recent call last):
File “/usr/lib/python2.7/runpy.py”, line 174, in _run_module_as_main
main”, fname, loader, pkg_name)
File “/usr/lib/python2.7/runpy.py”, line 72, in _run_code
exec code in run_globals
File “/home/boma/frappe-bench/apps/frappe/frappe/utils/bench_helper.py”, line 79, in
main()
File “/home/boma/frappe-bench/apps/frappe/frappe/utils/bench_helper.py”, line 16, in main
click.Group(commands=commands)(prog_name=‘bench’)
File “/home/boma/frappe-bench/env/local/lib/python2.7/site-packages/click/core.py”, line 716, in call
return self.main(*args, **kwargs)
File “/home/boma/frappe-bench/env/local/lib/python2.7/site-packages/click/core.py”, line 696, in main
rv = self.invoke(ctx)
File “/home/boma/frappe-bench/env/local/lib/python2.7/site-packages/click/core.py”, line 1060, in invoke
return _process_result(sub_ctx.command.invoke(sub_ctx))
File “/home/boma/frappe-bench/env/local/lib/python2.7/site-packages/click/core.py”, line 1060, in invoke
return _process_result(sub_ctx.command.invoke(sub_ctx))
File “/home/boma/frappe-bench/env/local/lib/python2.7/site-packages/click/core.py”, line 889, in invoke
return ctx.invoke(self.callback, **ctx.params)
File “/home/boma/frappe-bench/env/local/lib/python2.7/site-packages/click/core.py”, line 534, in invoke
return callback(*args, **kwargs)
File “/home/boma/frappe-bench/env/local/lib/python2.7/site-packages/click/decorators.py”, line 17, in new_func
return f(get_current_context(), *args, **kwargs)
File “/home/boma/frappe-bench/apps/frappe/frappe/commands/init.py”, line 24, in _func
ret = f(frappe._dict(ctx.obj), *args, **kwargs)
File “/home/boma/frappe-bench/apps/frappe/frappe/commands/site.py”, line 149, in install_app
_install_app(app, verbose=context.verbose)
File “/home/boma/frappe-bench/apps/frappe/frappe/installer.py”, line 142, in install_app
frappe.get_attr(after_install)()
File “/home/boma/frappe-bench/apps/erpnext/erpnext/setup/install.py”, line 14, in after_install
set_single_defaults()
File “/home/boma/frappe-bench/apps/erpnext/erpnext/setup/install.py”, line 37, in set_single_defaults
b.save()
File “/home/boma/frappe-bench/apps/frappe/frappe/model/document.py”, line 242, in save
return self._save(*args, **kwargs)
File “/home/boma/frappe-bench/apps/frappe/frappe/model/document.py”, line 269, in save
self.run_before_save_methods()
File “/home/boma/frappe-bench/apps/frappe/frappe/model/document.py”, line 710, in run_before_save_methods
self.run_method(“validate”)
File “/home/boma/frappe-bench/apps/frappe/frappe/model/document.py”, line 661, in run_method
return Document.hook(fn)(self, *args, **kwargs)
File “/home/boma/frappe-bench/apps/frappe/frappe/model/document.py”, line 839, in composer
return composed(self, method, *args, **kwargs)
File “/home/boma/frappe-bench/apps/frappe/frappe/model/document.py”, line 822, in runner
add_to_return_value(self, fn(self, *args, **kwargs))
File “/home/boma/frappe-bench/apps/frappe/frappe/model/document.py”, line 655, in
fn = lambda self, *args, **kwargs: getattr(self, method)(*args, **kwargs)
File “/home/boma/frappe-bench/apps/erpnext/erpnext/buying/doctype/buying_settings/buying_settings.py”, line 19, in validate
self.get(“supp_master_name”)==“Naming Series”, hide_name_field=False)
File “/home/boma/frappe-bench/apps/erpnext/erpnext/setup/doctype/naming_series/naming_series.py”, line 170, in set_by_naming_series
make_property_setter(doctype, “naming_series”, “reqd”, 0, “Check”)
File “/home/boma/frappe-bench/apps/frappe/frappe/custom/doctype/property_setter/property_setter.py”, line 70, in make_property_setter
property_setter.insert()
File “/home/boma/frappe-bench/apps/frappe/frappe/model/document.py”, line 231, in insert
self.run_post_save_methods()
File “/home/boma/frappe-bench/apps/frappe/frappe/model/document.py”, line 728, in run_post_save_methods
self.run_method(“on_update”)
File “/home/boma/frappe-bench/apps/frappe/frappe/model/document.py”, line 661, in run_method
return Document.hook(fn)(self, *args, **kwargs)
File “/home/boma/frappe-bench/apps/frappe/frappe/model/document.py”, line 839, in composer
return composed(self, method, *args, **kwargs)
File “/home/boma/frappe-bench/apps/frappe/frappe/model/document.py”, line 822, in runner
add_to_return_value(self, fn(self, *args, **kwargs))
File “/home/boma/frappe-bench/apps/frappe/frappe/model/document.py”, line 655, in
fn = lambda self, *args, **kwargs: getattr(self, method)(*args, **kwargs)
File “/home/boma/frappe-bench/apps/frappe/frappe/custom/doctype/property_setter/property_setter.py”, line 55, in on_update
validate_fields_for_doctype(self.doc_type)
File “/home/boma/frappe-bench/apps/frappe/frappe/core/doctype/doctype/doctype.py”, line 258, in validate_fields_for_doctype
validate_fields(frappe.get_meta(doctype, cached=False))
File “/home/boma/frappe-bench/apps/frappe/frappe/core/doctype/doctype/doctype.py”, line 456, in validate_fields
check_link_table_options(d)
File “/home/boma/frappe-bench/apps/frappe/frappe/core/doctype/doctype/doctype.py”, line 300, in check_link_table_options
frappe.throw(
(“Options must be a valid DocType for field {0} in row {1}”).format(d.label, d.idx))
File “/home/boma/frappe-bench/apps/frappe/frappe/init.py”, line 299, in throw
msgprint(msg, raise_exception=exc, title=title, indicator=‘red’)
File “/home/boma/frappe-bench/apps/frappe/frappe/init.py”, line 292, in msgprint
_raise_exception()
File “/home/boma/frappe-bench/apps/frappe/frappe/init.py”, line 265, in _raise_exception
raise raise_exception, encode(msg)
frappe.exceptions.ValidationError: Options must be a valid DocType for field Print Language in row 9

Please help… Thanks.
Boma